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XXIII. — A Contribution to our Knowledge of the Physical Projierties of 

 Methyl- Alcohol. By W. Dittmar, F.R.SS. Lond. & Edin., and Charles 

 A. Fawsitt. (Plate XXXIII.) 



(Read May 2, 1887.) 



Since its discovery by Dumas and Peligot in 1834, methyl-alcohol has 

 been the subject of a great many researches, and as a result we have long- 

 had a perfectly certain knowledge of its atomic composition, and a very 

 accurate knowledge of a great many of its reactions. Yet the physical 

 properties of the substance CH 4 have not yet been determined with a 

 satisfactory degree of precision. At this we need not wonder. For the 

 study of the transmutations of a species a very impure specimen may suffice, 

 and a series of such studies may leave no doubt about the correct atomic 

 formula of the species in question, and consequently also, if it is a volatile 

 substance, about its perfect gas density. But no other physical properties 

 can be determined otherwise than by direct experiments on a pure specimen. 

 And pure methyl- alcohol is very difficult to obtain. In whatever reasonable 

 sense we may take the word "pure," as attached to the name of a chemical 

 preparation, " pure " methyl-alcohol must be admitted to have been little more 

 than a chemical fiction until "Woiiler in 1852 discovered his well-known 

 (oxalate) process for its extraction from wood-spirit. 



As a consequence of this discovery, the properties of " methyl-alcohol " 

 suffered a remarkable change ; what had before been known as a more or 

 less unpleasantly smelling liquid, which boils at about 60° C, and turns brown 

 on treatment with caustic alkalies, assumed the form of an almost inodorous 

 liquid, boiling at or near 66° C, and behaving to caustic alkali pretty much 

 as pure ethyl-alcohol does. And it has since exhibited a fair degree of 

 constancy in its properties in the hands of numerous observers, although 

 the wood-spirits which these have used for their preparations must have been 

 of very different kinds. This tends to show that Wohler's alcohol (if carefully 

 prepared) is at least a fairly close approximation to the ideal substance, and 

 this impression is confirmed by a research of Kramer's, who prepared methyl- 

 alcohol from purified formate of methyl, and found it to boil at very nearly 

 66° C. 



The successive application of the oxalate and of the formate process would 

 probably yield a very pure preparation, because the former tends to eliminate 

 the more volatile, the latter the less volatile of the impurities ; and we very 



VOL. XXXIII. PART II. 4 F 



