112 Mr. Syme on a Substance from Coal Tar. [August, 



1 atom hydrocyanic acid 3-325 



1 atom iron 3-5 



6-825 



But the quantity of iron really present is only one half of what 

 this wei°'ht would indicate. This is the first compound which I 

 have met with that does not seem reconcilable to the atomic 

 theory. 1 invite chemists to the further investigation of it. 

 There are no facts so likely to lead to the improvement of the 

 science of chemistry as those which contradict our received 

 opinions. 



Glasgow, Jims 1, 1818. 



Article V. 



On a Substance from Coal Tar. By J. Syme, Esq. 



(To Dr. Thomson.) 



SIR Edinburgh, March 5, W\8. 



I take the liberty of sending you an account of a valuable 

 substance which may be obtained from coal tar. 



If you think it worthy of being made public, you will oblige 

 me by inserting it in your Annals of Philosophy. 



I am, Sir, your most obedient servant, 



J. Syme. 



As coat tar in every respect bears the strongest resemblance 

 to petroleum, it occurred to me that by distilling it a fluid might 

 be procured which, like naphtha, should have the property of 

 dissolving caoutchouc, and that in this way I should procure a 

 solvent free from the objections to which the known solvents of 

 that remarkable substance are all more or less liable. 



To ascertain this, I subjected a quantity of coal tar to distilla- 

 tion in a o-lass retort and receiver with a moderate heat. When 

 the fluid which came over amounted in bulk to about one third 

 of the tar operated on, I put a stop to the process. 



Upon examining the product, I found that it was not homoge- 

 neous, but consisted of two differently coloured fluids, quite 

 distinct (as oil and water from each other when allowed to remain 

 together without agitation), and which consisted in nearly equal 

 quantities. 



Having separated these in the common way, by means of a 

 funnel 1 examined the properties of each. The one supernatant 

 was of a dark amber colour, and had a strong, peculiar, pene- 

 trating odour. A piece of paper soaked in it when inflamed 



