Since my last post I have done a little more reading, which has been most interesting, but not substantially changed by conclusion.
Biringuccio says about Antimony:
“The practical philosophers make great use of it in their alchemistic works, in order, they say, to make an oil that they believe gives the colour of gold to fixed silver. For this reason many of them hold it in high repute, especially the kind that has long thin fibres like a bundle of bristles. And they say that they can obtain greater results with it than Sulphur, since it is nearer the metallic species than sulphur is. This I know for certain because I have seen them extract from it a bloody liquor in the form of an oil. The alchemist who made that which I saw told me that it had not only the property of giving a golden colour to silver but also the properly of fixing silver. This may be true, but as I said, I have seen only the liquor, and I have never seen silver coloured by it or anything else.”
He also mentions that it was mined and used in Pewter and bells. Interestingly enough, one article in the journal of the Historical Mettallurgy Society says that many Bronze cooking vessels in the medieval period had around 5% Antimony, but that it was most likely from the use of Copper ore rich in Antimony. Unfortunately none of my information sources mention the use of Antimony in pewter.
Biringuccio was writing in the 1530’s, so we can safely say that Antimony was then in use by Alchemists. This pushes its use back to the early 16th century. Now of course it would be really interesting to know who was actually using it, but it is hard to find real evidence of alchemy from the 15th century. We have some, but it is not very informative, at least not in the way I want.
Or do we?
I have also found a translation of a text about Antimony which purports to have been written by Roger Bacon, called “Tract on the tincture and oil of Antimony”, apparently from a German book published in the 17th century.
http://www.levity.com/alchemy/rbacon2.html
Of course it is not likely to have been written by Roger Bacon, since he was around in the 13th century, and many texts were written by people who wanted to give them false authority and antiquity (It being a general tenet of Alchemy that the ancients had quite a few people who knew the secret, thus old texts were better than new ones), and thus affixed the name of someone like Roger Bacon to them.
Given what I quote Biringuccio as saying above, it is interesting to find that the aforementioned tract says:
“Several poor and common Laborers, when they have prepared the Antimonium thus, have taken one part out, to take care of their expenses, so that they may more easily do the rest of the work and complete it, They then mixed it with one part Salmiac, one part Vitro (alii. Nitro, alii. Titro), one part Rebohat, to cleanse the Corpera, and then proceeded to project this mixture onto a pure Lunam. And if the Luna was one Mark, they found two and a half Loth good gold after separation; sometimes even more. And therewith they had accomplished a work providing for their expenses, so that they might even better expect to attain to the Great Work. And the foolish called this a bringing into the Lunam, but they are mistaken. For such gold is not brought in by the Spiritibus (alii. Speciebus), but any Luna contains two Mark gold to the Loth, some even more. But this gold is united to the Lunar nature to such a degree that it may not be separated from it, neither by Aquafort, nor by common Antimonium, as the goldsmiths know. When however the just mentioned mixture is thrown onto the Lunam in flux, then such a separation takes place that the Luna quite readily gives away her implanted gold either in Aquafort or in Regal, and lets herself separate from it, strikes it to the ground and precipitates it, which would or might otherwise not happen. Therefore it is not a bringing into the Lunam, but a bringing out of the Luna.”
What this looks like to me is a recipe for preparing an Antimonial solution, which when added to Silver makes something that looks like gold. The moon is usually Silver, at least according to my familiarity with Alchemy, gold being called the Sun.
What is more amusing is that on the levity.com website from which the above quote is taken, is mention of “The secret book of Artephius”,
http://www.levity.com/alchemy/artephiu.html
This was allegedly written in the 12th century, and translated by someone called “Lapidus”, who published a book called “In pursuit of Gold” in 1976. Oddly enough, I can find no other mention of Artephius online, except connected to this “In pursuit of gold”, or in other words, this person and manuscript may well not exist. Neither of my two modern books on Alchemy mention Lapidus or Artephius. The book of Artephius apparently describes the use of Antimony to do the usual Alchemical operations.
The mystery becomes farcical when you read this thread from the Levity.com archives, about Lapidus:
http://www.levity.com/alchemy/t_lapid.html
In summary, someone asks if Lapidus is still alive and going to publish something else, and if he is a certain named person. One person replied that he was dead, and not the named person. Someone else then replied that Lapidus was in fact alive, and possibly going to publish another book soon.
This goes to show the confusion that surrounds the modern practise of Alchemy, and the opportunities for fraud and lies. Which is a shame.
Friday, September 14, 2007
What things do I not know much about in Alchemy?
OK, lots of things I don’t know about in Alchemy. Nevertheless, there are couple of questions that I wonder what the answers are.
For starters, there is the change over from mercury to antinomy in the 16th century. At the beginning of the century we have James 4th of Scotland’s pet alchemist buying mercury, and using some gold and other chemicals, but no mention of Antimony. By the beginning of the next century, with the publication of a book called “The triumphal chariot of Alchemy” we have them using Antimony. When and why did that happen?
Moreover we have Newton, (who died in 1727) spending a great deal of time on Alchemy, often locking himself in his room for days at a time and producing copious notes on all the alchemical texts he could find. He produced the Star regulus of Antimony, a crystalline form of antimony. More information can be found here:
http://webapp1.dlib.indiana.edu/newton/reference/chemProd.do
The earliest mention I have of Antimony is in the 12 Keyes of Basil Valentine. Now, according to the preface in a reprinted Llanerch edition of selections from “The Hermetic Museum”, (Itself first published in 1625) Basil Valentine was a Benedictine Monk, and various people place him around the 1490’s. However this is clearly wrong, I will explain why shortly, yet the writer of the preface of my Llanerch edition accepts this personage as being genuine. By contrast, John Read (Through alchemy to Chemistry”, published in 1957, and coincidentally a professor of Chemistry at St Andrews) points out that the first copy of any texts by Basil Valentine are dated to 1599.
The text in question runs:
“Take a fierce grey wolf, which, though on account of its name it be subject to the way of warlike Mars, is by birth the offspring of ancient Saturn, and is found in the valleys and mountains of the world, where he roams about savage with hunger. Cast to him the body of the King, and when he has devoured it, burn him entirely to ashes in a great fire. By this process the King will have been liberated; and when it has been performed thrice the Lion has overcome the wolf and will find nothing more to devour in him. Thus our body has been rendered fit for the first stage of our work.”
Read says that the grey wolf is Antimony Sulphide, or Stibnite, an antimony ore, known as the wolf of the metals because of its ability to unite with all the alchemical metals except gold. The repeated fusion of it with gold could be used as a purifying method for the gold.
Now, what makes me sure that Basil vValentine, or rather whoever was writing under that name (Read suggests that a Johann Tholde, a Frankenhausen salt maker was perhaps the author) was writing in the later 16th century is that he insists upon three elements, Mercury, Sulphur and Salt. This is a Paracelsian formulation. Paracelsus, who died in 1541, is famous for his views of alchemy and chemistry, and I am sure that you have all heard something about him. But anyway, as far as I have read, he is the one who introduced the idea of Salt, as well as the other two, whereas before him alchemists used just Mercury and Sulphur. So this Basil Valentine is most likely a late 16th century person.
This is made clearer by the fact that someone, calling themselves Basil Valentine, wrote “The triumphal Chariot of Antimony”, published in 1604. This, according to Read is probably the first monograph on a chemical element.
This still does not explain why Alchemists started using Antimony. It may be that they had been using it for many years, but somehow, amongst all the confusion of alchemical writings, this has not been noticed. Somehow I doubt that though.
“Chemistry of the elements” an otherwise excellent textbook, falls for the claims of Basil Valentine being around in the 15th century, but has some useful information, viz: stibnite was used as a black eye colouring in Biblical times, and it may be that it was isolated by Albertus Magnus in the early 13th century. There is apparently mention of an antimonium by Jabir in ~800.
When I turn to “De Re Metallica” I find that Antimony is mentioned as being something you can smelt, but there is little detail. We can therefore be sure that it was around as a separate element in the 16th century, but there is little evidence to suggest it was widely known and used before that period.
So I think it reasonable that Alchemists noticed the properties of Antimony some time during the 1500’s, and it found its way into their everyday use, but in which country and decade this was done, and who popularized it, is unknown.
By comparison, in Thomas Norton’s treatise on Alchemy, which is also in “The Hermetic Museum”, is definitely dated to 1477, and although I have not read and understood it fully, it seems to lack reference to Antimony, instead talking about the usual Alchemical Sulphur, Mercury, quicklime, Magnesia and others. It does show that by the late 15th century such people were taking a close interest in operations on all sorts of minerals and metals, which can be seen in fruition in Agricola’s “De Re Metallica” 70 years later.
The annoying thing is that my question is likely never to be answered, due simply to lack of evidence.
The second question I am interested in is the change to a fully internal self development method of philosophy by allegory. By the 17th century this was pretty much complete, Alchemy was divorcing itself from chemistry and was almost wholly magical in a way which it had not been before. Before, there was some relationship to the real world. By the end, there was not, it was all allegorical. It is clear that by the later medieval period Alchemy was splitting up into various strands, from the purely spiritual to the practical, (And separate from all that we had the artisans who worked with material stuff all day refining their techniques and understanding of what things did, even if they didn’t write it down or produce an overarching scientific theory)
*Chemical note on Antimony: Antimony is an element in the same group as Nitrogen. Below Nitrogen we have Phosphorous, Arsenic, Antimony and then Bismuth. The last three are poisonous. Antimony is one step along from Tin, and is a silvery coloured metal like Tin, and has an atomic weight of 121.75. It is thus one of the densest metals that they would have had access to, in increasing weight they had- Silver, Tin, Antimony, Gold, Mercury, lead and Bismuth, and apparently they were casting Bismuth to make type up for early printing presses in the 15th century.
Antimony is used in lead batteries to help stabilize the sheets of lead, bearings, ammunition, and some electronics thingies e.g. diodes.
For starters, there is the change over from mercury to antinomy in the 16th century. At the beginning of the century we have James 4th of Scotland’s pet alchemist buying mercury, and using some gold and other chemicals, but no mention of Antimony. By the beginning of the next century, with the publication of a book called “The triumphal chariot of Alchemy” we have them using Antimony. When and why did that happen?
Moreover we have Newton, (who died in 1727) spending a great deal of time on Alchemy, often locking himself in his room for days at a time and producing copious notes on all the alchemical texts he could find. He produced the Star regulus of Antimony, a crystalline form of antimony. More information can be found here:
http://webapp1.dlib.indiana.edu/newton/reference/chemProd.do
The earliest mention I have of Antimony is in the 12 Keyes of Basil Valentine. Now, according to the preface in a reprinted Llanerch edition of selections from “The Hermetic Museum”, (Itself first published in 1625) Basil Valentine was a Benedictine Monk, and various people place him around the 1490’s. However this is clearly wrong, I will explain why shortly, yet the writer of the preface of my Llanerch edition accepts this personage as being genuine. By contrast, John Read (Through alchemy to Chemistry”, published in 1957, and coincidentally a professor of Chemistry at St Andrews) points out that the first copy of any texts by Basil Valentine are dated to 1599.
The text in question runs:
“Take a fierce grey wolf, which, though on account of its name it be subject to the way of warlike Mars, is by birth the offspring of ancient Saturn, and is found in the valleys and mountains of the world, where he roams about savage with hunger. Cast to him the body of the King, and when he has devoured it, burn him entirely to ashes in a great fire. By this process the King will have been liberated; and when it has been performed thrice the Lion has overcome the wolf and will find nothing more to devour in him. Thus our body has been rendered fit for the first stage of our work.”
Read says that the grey wolf is Antimony Sulphide, or Stibnite, an antimony ore, known as the wolf of the metals because of its ability to unite with all the alchemical metals except gold. The repeated fusion of it with gold could be used as a purifying method for the gold.
Now, what makes me sure that Basil vValentine, or rather whoever was writing under that name (Read suggests that a Johann Tholde, a Frankenhausen salt maker was perhaps the author) was writing in the later 16th century is that he insists upon three elements, Mercury, Sulphur and Salt. This is a Paracelsian formulation. Paracelsus, who died in 1541, is famous for his views of alchemy and chemistry, and I am sure that you have all heard something about him. But anyway, as far as I have read, he is the one who introduced the idea of Salt, as well as the other two, whereas before him alchemists used just Mercury and Sulphur. So this Basil Valentine is most likely a late 16th century person.
This is made clearer by the fact that someone, calling themselves Basil Valentine, wrote “The triumphal Chariot of Antimony”, published in 1604. This, according to Read is probably the first monograph on a chemical element.
This still does not explain why Alchemists started using Antimony. It may be that they had been using it for many years, but somehow, amongst all the confusion of alchemical writings, this has not been noticed. Somehow I doubt that though.
“Chemistry of the elements” an otherwise excellent textbook, falls for the claims of Basil Valentine being around in the 15th century, but has some useful information, viz: stibnite was used as a black eye colouring in Biblical times, and it may be that it was isolated by Albertus Magnus in the early 13th century. There is apparently mention of an antimonium by Jabir in ~800.
When I turn to “De Re Metallica” I find that Antimony is mentioned as being something you can smelt, but there is little detail. We can therefore be sure that it was around as a separate element in the 16th century, but there is little evidence to suggest it was widely known and used before that period.
So I think it reasonable that Alchemists noticed the properties of Antimony some time during the 1500’s, and it found its way into their everyday use, but in which country and decade this was done, and who popularized it, is unknown.
By comparison, in Thomas Norton’s treatise on Alchemy, which is also in “The Hermetic Museum”, is definitely dated to 1477, and although I have not read and understood it fully, it seems to lack reference to Antimony, instead talking about the usual Alchemical Sulphur, Mercury, quicklime, Magnesia and others. It does show that by the late 15th century such people were taking a close interest in operations on all sorts of minerals and metals, which can be seen in fruition in Agricola’s “De Re Metallica” 70 years later.
The annoying thing is that my question is likely never to be answered, due simply to lack of evidence.
The second question I am interested in is the change to a fully internal self development method of philosophy by allegory. By the 17th century this was pretty much complete, Alchemy was divorcing itself from chemistry and was almost wholly magical in a way which it had not been before. Before, there was some relationship to the real world. By the end, there was not, it was all allegorical. It is clear that by the later medieval period Alchemy was splitting up into various strands, from the purely spiritual to the practical, (And separate from all that we had the artisans who worked with material stuff all day refining their techniques and understanding of what things did, even if they didn’t write it down or produce an overarching scientific theory)
*Chemical note on Antimony: Antimony is an element in the same group as Nitrogen. Below Nitrogen we have Phosphorous, Arsenic, Antimony and then Bismuth. The last three are poisonous. Antimony is one step along from Tin, and is a silvery coloured metal like Tin, and has an atomic weight of 121.75. It is thus one of the densest metals that they would have had access to, in increasing weight they had- Silver, Tin, Antimony, Gold, Mercury, lead and Bismuth, and apparently they were casting Bismuth to make type up for early printing presses in the 15th century.
Antimony is used in lead batteries to help stabilize the sheets of lead, bearings, ammunition, and some electronics thingies e.g. diodes.
Monday, April 23, 2007
Colouring glass
Since making my own glass seems very hard to do, I have cheated a bit. With my furnace up around 950 to 1,000 degrees, I can melt normal modern bottle glass. So as a test today I tried to colour some glass, by means of rust.
You see, iron makes glass green in colour. Green glass was produced regularly in England, because they used yellow sand which has a high iron content, as little as 0.5% colouring the glass green. If you wanted really clear glass you had to use white sand or quartz, which were not widely found in the UK, more often found in Germany. However all through the medieval period window glass was imported from the continent.
A somewhat green british glass alembic can be seen here:
(From: http://www.exeter.gov.uk/timetrail/07_middleages/object_detail.asp?photoref=7_89, Exeter during the middle ages)
This is the glass before:
Sitting in a crucible of my own manufacture that has survived at least one firing up to the correct temperature.
So, I melted the glass to a gooey consistency, then dropped some rust on top, and stuck it back in the furnace for ten minutes more. After that time I took it out, partly because I was running out of fuel. The end result was this:
It’s not very exciting, is it? There was not enough time for the iron to diffuse through the glass, and also I had not mixed the metal in properly. Nevertheless a green tint should be visible. This is a fairly simple demonstration that I could carry out at an event without any trouble, especially if I mixed the iron into the glass properly. Moreover, different colours can be had with different additives.
You see, iron makes glass green in colour. Green glass was produced regularly in England, because they used yellow sand which has a high iron content, as little as 0.5% colouring the glass green. If you wanted really clear glass you had to use white sand or quartz, which were not widely found in the UK, more often found in Germany. However all through the medieval period window glass was imported from the continent.
A somewhat green british glass alembic can be seen here:
(From: http://www.exeter.gov.uk/timetrail/07_middleages/object_detail.asp?photoref=7_89, Exeter during the middle ages)
This is the glass before:
Sitting in a crucible of my own manufacture that has survived at least one firing up to the correct temperature.
So, I melted the glass to a gooey consistency, then dropped some rust on top, and stuck it back in the furnace for ten minutes more. After that time I took it out, partly because I was running out of fuel. The end result was this:
It’s not very exciting, is it? There was not enough time for the iron to diffuse through the glass, and also I had not mixed the metal in properly. Nevertheless a green tint should be visible. This is a fairly simple demonstration that I could carry out at an event without any trouble, especially if I mixed the iron into the glass properly. Moreover, different colours can be had with different additives.
The difficulties of finding original sources (and medieval fire retardant part 3)
Those of you who recall my last experiments making alleged fire retardant will remember that I found information about it in the journal of the Historical Metallurgy society, in an article by Jochem Walters. With regards to the fire retardant he says:
Un-slaked lime has been a component of widely varied fire-proof products throughout the modern period. See the Curioser Kunstler (1 133/257/305/348)
There was an e-mail address at the bottom of the article, so I mailed him a couple of weeks ago, and received a reply.
He said that the Kurioser Kunstler was the largest collection of recipes for all sorts of things, and was published by Johann Kunckel von Loewenstjern, anonymously in Nuremberg in 1696. The full title being „Der Curieusen Kunst- und Werck-Schule
erster und anderer Theil“
Now, Kunst translates roughly as art, and I think a rough translation would read “The curious art and work something something something. (OK, I’m going to have to ask Lukas what this means)
It was translated by Robert Dossie in “The Handmaid to the Arts”, vol. 2, 1750, with various editions published later in the century. Now, it would be really good if I could get a copy of this, unfortunately there are not any I can find online for sale. Apparently they are very rare. But another of his books is available for only £150.
Nobody appears to have re-published it since the 18th century. I am finding this is a very common problem, whether I am after translations of Geber, or some 25th century alchemical works, it seems the last full reprinting was often done in the 17th or 18th centuries. Which is only to be expected, but it means that for someone like me who I only dabbling in it, information is very hard to come by.
Un-slaked lime has been a component of widely varied fire-proof products throughout the modern period. See the Curioser Kunstler (1 133/257/305/348)
There was an e-mail address at the bottom of the article, so I mailed him a couple of weeks ago, and received a reply.
He said that the Kurioser Kunstler was the largest collection of recipes for all sorts of things, and was published by Johann Kunckel von Loewenstjern, anonymously in Nuremberg in 1696. The full title being „Der Curieusen Kunst- und Werck-Schule
erster und anderer Theil“
Now, Kunst translates roughly as art, and I think a rough translation would read “The curious art and work something something something. (OK, I’m going to have to ask Lukas what this means)
It was translated by Robert Dossie in “The Handmaid to the Arts”, vol. 2, 1750, with various editions published later in the century. Now, it would be really good if I could get a copy of this, unfortunately there are not any I can find online for sale. Apparently they are very rare. But another of his books is available for only £150.
Nobody appears to have re-published it since the 18th century. I am finding this is a very common problem, whether I am after translations of Geber, or some 25th century alchemical works, it seems the last full reprinting was often done in the 17th or 18th centuries. Which is only to be expected, but it means that for someone like me who I only dabbling in it, information is very hard to come by.
Monday, March 5, 2007
Medieval fire retardant?
In the last issue of the journal of the Historical Metallurgy society, there was an article on a Byzantine gold smiths manual from the 11th century. Amongst many other things in the manual was a recipe that translated, said:
My attention was caught by this, and I began to wonder what it was and whether it actually worked.
The article’s author only had this to say about the recipe:
Un-slaked lime has been a component of widely varied fire-proof products throughout the modern period. See the Curioser Kunstler (1 133/257/305/348)
Not enough for my curiosity. So I decided to try and replicate the recipe.
Now, at first sight it looks pretty silly. Oil and quicklime? The oil would prevent the quicklime from contact with water, but then if you distilled it with a caustic solution, what you would get might well be a solution of metallic salts, which when put onto cloth would result in, when dried, a layer of metal complex salts that I suppose would retard combustion a bit.
I set up my furnace as below, with the pot containing the ingredients sitting on top of some broken bricks, to raise it above the flames.
I mixed 30 grams of quicklime with olive oil, being what I had handy. Then I mixed some sodium hydroxide crystals with water, and poured that in as well. It started boiling over pretty quickly after I put it in the flames, and I lost a fair bit of vapour that did not condense out, although it was probably water. After about 20 minutes I stopped the process, and what was left in the bottom of the vessel was a lump of slightly foamed material.
What had come over was liquid, and smelt funny. It was perhaps a little bit more gloopy than I would expect for plain water.
So I dipped several pieces of linen into the liquid and dried them. They all burnt, although just a little bit slower than normal. This was not good, but not unexpected given the uncertain nature of what I was attempting. The recipe says to expose them to the fire after dipping them in the solution, but seeing as you can get the same effects by dipping the cloth in water, I figure that the liquid is supposed to form a coating. After all, a fire retardant coating would be useful on something like an apron, which comes close to a fire regularly, but it would be very impractical to keep it wet all the time.
After some googling and reading up on things, it appears that linseed oil would be the best to use, there being mention of its use in fireproof glue.
(http://www.wholesaleexporter.com/fireproof-glue.htm)
It also seems that anaerobically heating linseed oil to 300C makes it polymerize. I think that such a polymerized oil would not be so easily burnt, and would thus act as a fire retardant. In fact some polymers are sold as fire proof, because they are highly polymerized and their outer layers are already reacted with oxygen during the manufacturing stage, meaning there is nothing that will catch fire, unless you apply so much heat as to break down the polymer chains themselves.
So next time I shall use linseed oil, and boil it for longer at higher temperatures. This should help isolate the exact way this works. Possibly the action of the lime and sodium hydroxide solution is to keep the linseed oil isolated from the atmosphere enough to begin polymerizing. Or maybe not. It is frustratingly unclear.
Another mysterious method
Take unslaked lime, mix oil into the lime, wetting it as thoroughly once or twice. Then pour it into a distillation vessel. Also add a caustic solution [?] whereby you pour it all over until it is 2 fingers deep. Now fill this divine water into another flagon. After that, take a linen cloth and dampen it with this water and expose it to the fire. If the cloth burns, you know that it was not prepared well. Make the lime preparation again with other un-slaked lime and repeat as before until successful, ie until the fabric no longer catches fire.
My attention was caught by this, and I began to wonder what it was and whether it actually worked.
The article’s author only had this to say about the recipe:
Un-slaked lime has been a component of widely varied fire-proof products throughout the modern period. See the Curioser Kunstler (1 133/257/305/348)
Not enough for my curiosity. So I decided to try and replicate the recipe.
Now, at first sight it looks pretty silly. Oil and quicklime? The oil would prevent the quicklime from contact with water, but then if you distilled it with a caustic solution, what you would get might well be a solution of metallic salts, which when put onto cloth would result in, when dried, a layer of metal complex salts that I suppose would retard combustion a bit.
I set up my furnace as below, with the pot containing the ingredients sitting on top of some broken bricks, to raise it above the flames.
I mixed 30 grams of quicklime with olive oil, being what I had handy. Then I mixed some sodium hydroxide crystals with water, and poured that in as well. It started boiling over pretty quickly after I put it in the flames, and I lost a fair bit of vapour that did not condense out, although it was probably water. After about 20 minutes I stopped the process, and what was left in the bottom of the vessel was a lump of slightly foamed material.
What had come over was liquid, and smelt funny. It was perhaps a little bit more gloopy than I would expect for plain water.
So I dipped several pieces of linen into the liquid and dried them. They all burnt, although just a little bit slower than normal. This was not good, but not unexpected given the uncertain nature of what I was attempting. The recipe says to expose them to the fire after dipping them in the solution, but seeing as you can get the same effects by dipping the cloth in water, I figure that the liquid is supposed to form a coating. After all, a fire retardant coating would be useful on something like an apron, which comes close to a fire regularly, but it would be very impractical to keep it wet all the time.
After some googling and reading up on things, it appears that linseed oil would be the best to use, there being mention of its use in fireproof glue.
(http://www.wholesaleexporter.com/fireproof-glue.htm)
It also seems that anaerobically heating linseed oil to 300C makes it polymerize. I think that such a polymerized oil would not be so easily burnt, and would thus act as a fire retardant. In fact some polymers are sold as fire proof, because they are highly polymerized and their outer layers are already reacted with oxygen during the manufacturing stage, meaning there is nothing that will catch fire, unless you apply so much heat as to break down the polymer chains themselves.
So next time I shall use linseed oil, and boil it for longer at higher temperatures. This should help isolate the exact way this works. Possibly the action of the lime and sodium hydroxide solution is to keep the linseed oil isolated from the atmosphere enough to begin polymerizing. Or maybe not. It is frustratingly unclear.
Friday, March 2, 2007
Calcining lime and ashes
At last, doing what my blog is named after
I bought some garden lime a few weeks ago, which is basically crushed limestone. Limestone is calcium carbonate, CaCO3, and needs to be burnt in order to convert it to CO, calcium oxide, or quicklime. This is caustic (Alkaline), and used for destroying stuff. Also, if you mix it with water in the approved manner, you get lime mortar. Which then, over the years after it has been applied, absorbs CO2 from the air to become calcium carbonate again. All you are doing is making limestone into a form that is easily used for building, and then letting it turn back into limestone once in place.
I need it for several things. To start with, one or two odd chemical recipes require quicklime. (More on them this weekend) Furthermore, I want to see what I can produce and how much and how quickly, to get an idea of lime kilns and their work, and also whether I can make enough to do interesting things with. For example, it would be good to demonstrate making slaked lime (That’s the calcium hydroxide you get by adding water to the calcium oxide) and then using it to stick a couple of stones together.
Today’s take home fact is that lime mortar is re-usable, you just have to burn it.
Procedure:
Take two bits of scrap stainless steel from work. Place lime onto them. Get fire going, and heat up furnace to well over 1,000C. Hold at that temperature for half an hour. Stir lime occasionally. At this stage it should be so hot that any wood you put into the furnace bursts straight into flames.
Working a lime kiln must have been very hot, sweaty work. Holding over 1,000C for days at a time, with mixes of lime and coke or coal or wood tipped in the top would have been hard work. You can still see a lot of limekilns around Scotland, when local supplies of lime were exploited in the 18th and 19th centuries, in order to improve the farmland and build more houses. They are made of brick or stone, and are generally set against a bank or hill in order to make it easy to tip the mix of coal and limestone into the top of the furnace. After some time the material would have sunk to the bottom of the furnace, where I assume it was tapped to allow the lime out, although there would have to be holes to allow air in as well. I cannot find anything useful online about how lime kilns worked.
Regular readers will have noticed my grousing about a lack of reactions between some sand and boiled ashes. So during last week I decided to calcine the ashes I had in order to purify them. The end result was a much smaller amount of brown stuff. They lost 38% of their weight. Now, I am assuming that this was mostly carbon compounds that were oxidized readily in the over 1,000C temperatures that they reached.
The photo below shows the steel sitting in the furnace, which is glowing warmly.
Further information on Lime can be found at these places:
The Scottish Lime centre
Charlestown lime kilns
I bought some garden lime a few weeks ago, which is basically crushed limestone. Limestone is calcium carbonate, CaCO3, and needs to be burnt in order to convert it to CO, calcium oxide, or quicklime. This is caustic (Alkaline), and used for destroying stuff. Also, if you mix it with water in the approved manner, you get lime mortar. Which then, over the years after it has been applied, absorbs CO2 from the air to become calcium carbonate again. All you are doing is making limestone into a form that is easily used for building, and then letting it turn back into limestone once in place.
I need it for several things. To start with, one or two odd chemical recipes require quicklime. (More on them this weekend) Furthermore, I want to see what I can produce and how much and how quickly, to get an idea of lime kilns and their work, and also whether I can make enough to do interesting things with. For example, it would be good to demonstrate making slaked lime (That’s the calcium hydroxide you get by adding water to the calcium oxide) and then using it to stick a couple of stones together.
Today’s take home fact is that lime mortar is re-usable, you just have to burn it.
Procedure:
Take two bits of scrap stainless steel from work. Place lime onto them. Get fire going, and heat up furnace to well over 1,000C. Hold at that temperature for half an hour. Stir lime occasionally. At this stage it should be so hot that any wood you put into the furnace bursts straight into flames.
Working a lime kiln must have been very hot, sweaty work. Holding over 1,000C for days at a time, with mixes of lime and coke or coal or wood tipped in the top would have been hard work. You can still see a lot of limekilns around Scotland, when local supplies of lime were exploited in the 18th and 19th centuries, in order to improve the farmland and build more houses. They are made of brick or stone, and are generally set against a bank or hill in order to make it easy to tip the mix of coal and limestone into the top of the furnace. After some time the material would have sunk to the bottom of the furnace, where I assume it was tapped to allow the lime out, although there would have to be holes to allow air in as well. I cannot find anything useful online about how lime kilns worked.
Regular readers will have noticed my grousing about a lack of reactions between some sand and boiled ashes. So during last week I decided to calcine the ashes I had in order to purify them. The end result was a much smaller amount of brown stuff. They lost 38% of their weight. Now, I am assuming that this was mostly carbon compounds that were oxidized readily in the over 1,000C temperatures that they reached.
The photo below shows the steel sitting in the furnace, which is glowing warmly.
Further information on Lime can be found at these places:
The Scottish Lime centre
Charlestown lime kilns
Sal Alkali and glass making
So, wondering what Sal Alkali is for? Simple- it and quartz sand are all you need to make glass. Oh, and a furnace capable of over 1,000 degrees, maybe a bit more. Have I mentioned that I like working with fire?
What I have done over the past few weeks was produce alkaline powder by burning beech wood. (see previous posts about this and sourcing the wood) Theophilus says to use ashes, but I wanted to see how much salt I could produce, since by the early 16th century glassmakers were certainly making the salt, rather than just using ashes. This has the advantage of meaning you have more control over the glass and what is in it, since simply using the ashes means you can end up with bits of earth and suchlike from the original material, such as bracken roots. (See previous post)
The end result was, not a lot of salt.
I faithfully took the ashes, and boiled them up in a pot, until they were dry, and had turned into a fine gray powder. This powder tested at a pH of about 10, so definitely had some caustic properties in it. I suspect it has a mix of sodium and potassium salts as well as bits of charcoal and other things.
So, to make glass, I weighed out 20grams of ordinary sand with 10 grams of the salt I had previously made. I mixed it up as much as possible, then placed it in the pot you can see in the picture below:
The furnace was set up with a 2 brick deep volume for the charcoal, and the bellows in their usual place. Then, with it lit, I bellowed it up to over 1,000C in an hour or so. It takes a long time to reach thermal equilibrium between the inside and outside of the furnace. With the crucible inside, and glowing red, I held it at 1030-1050 for 10 minutes, and stirred the sand/ salts mix occasionally. It definitely fizzed a little around the thousand mark, and oddly enough potassium carbonate melts at 980C…
This photo shows the pot in use:
The problem was that the pot actually cracked during use. It has since split into several parts, and it is clear that it is too thick, and could not cope with the different heating rates of different parts of the pot. Fortunately I did not lose any of the fritted mixture.
In this photo you can see the two ingredients and what they combined to make. The sand is at the top, the boiled ashes to the bottom right, and the fritted material to the bottom left. It doesn’t look very good I am afraid.
Next time I shall heat it up to over 1,000C, and mix in more boiled ashes. I suspect that the percentage of sodium and potassium salts might not be high enough, so if I mix more in I stand a better chance of getting the sand to melt. The salts melt at a lower temperature and act as a flux, taking the sand (silica) into solution at a much lower temperature. Otherwise I would have to go to at least 1600C for silica to melt. Which is impossible with my set up.
Next time I shall hopefully get a nice blob of glass.
What I have done over the past few weeks was produce alkaline powder by burning beech wood. (see previous posts about this and sourcing the wood) Theophilus says to use ashes, but I wanted to see how much salt I could produce, since by the early 16th century glassmakers were certainly making the salt, rather than just using ashes. This has the advantage of meaning you have more control over the glass and what is in it, since simply using the ashes means you can end up with bits of earth and suchlike from the original material, such as bracken roots. (See previous post)
The end result was, not a lot of salt.
I faithfully took the ashes, and boiled them up in a pot, until they were dry, and had turned into a fine gray powder. This powder tested at a pH of about 10, so definitely had some caustic properties in it. I suspect it has a mix of sodium and potassium salts as well as bits of charcoal and other things.
So, to make glass, I weighed out 20grams of ordinary sand with 10 grams of the salt I had previously made. I mixed it up as much as possible, then placed it in the pot you can see in the picture below:
The furnace was set up with a 2 brick deep volume for the charcoal, and the bellows in their usual place. Then, with it lit, I bellowed it up to over 1,000C in an hour or so. It takes a long time to reach thermal equilibrium between the inside and outside of the furnace. With the crucible inside, and glowing red, I held it at 1030-1050 for 10 minutes, and stirred the sand/ salts mix occasionally. It definitely fizzed a little around the thousand mark, and oddly enough potassium carbonate melts at 980C…
This photo shows the pot in use:
The problem was that the pot actually cracked during use. It has since split into several parts, and it is clear that it is too thick, and could not cope with the different heating rates of different parts of the pot. Fortunately I did not lose any of the fritted mixture.
In this photo you can see the two ingredients and what they combined to make. The sand is at the top, the boiled ashes to the bottom right, and the fritted material to the bottom left. It doesn’t look very good I am afraid.
Next time I shall heat it up to over 1,000C, and mix in more boiled ashes. I suspect that the percentage of sodium and potassium salts might not be high enough, so if I mix more in I stand a better chance of getting the sand to melt. The salts melt at a lower temperature and act as a flux, taking the sand (silica) into solution at a much lower temperature. Otherwise I would have to go to at least 1600C for silica to melt. Which is impossible with my set up.
Next time I shall hopefully get a nice blob of glass.
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