ON A TEST FOR METHYLIC ALCOHOL. 
217 
course, be no change of colour, therefore, it would be reasoned, there was no 
.naphtha present. On the other hand, a spirit of wine containing oils or organic 
matter in solution would be readily coloured by the caustic alkali, from which 
it would be inferred to contain or consist entirely of naphtha. The fallacies of 
the test will be rendered still more evident when I state that Escliwege’s patent 
naphtha and pure spirit of wine are not at all coloured by alkalies. 
A test quite as good as Ure’s will be found in strong sulphuric acid. If a drop 
each of spirit of wine, patent naphtha, ordinary naphtha, and methylated spirit, 
are placed separately on a white slab, and a drop of sulphuric acid added to each, 
the dark coloration produced will readily distinguish the ordinary naphtha and 
methylated spirit from the patent naphtha and the spirit of wine ; the naphtha 
itself will be indicated by a very dark colour, the methylated spirit by a much 
lighter one, whilst the spirit of wine and patent naphtha will be totally unal¬ 
tered. 
The difference in the boiling-point of absolute alcohol and absolute methylated 
spirit is so slight, only 4° of Fahrenheit (methylated spirit boiling at 169°, alco¬ 
hol at 173°), and its exact determination being somewhat difficult, I do not 
think this difference is of much practical value, although a spirit boiling at less 
than 172° would certainly not be pure alcohol, but then on the other hand, it 
would not necessarily follow that it contained naphtha. 
It occurred to me early in my experimental trials, that there was a possibility 
of a test being based upon some difference in one or other of the ethers of the 
respective alcohols, but after many trials I have not met with any success in this 
direction. Without enumerating them, I should perhaps state here that most 
of the methylic ethers are remarkably similar in properties to the corresponding 
ethylic ethers ; and when there is a difference, it is of such a nature that it is 
not at all applicable as a test. The only one I had strong hopes of being suc¬ 
cessful with was the methyl-oxalic ether. This is formed on submitting naphtha 
to the action of about its own weight of sulphuric and a like quantity of oxalic 
acids and then distilling, and occurs in the form of transparent, colourless, 
rhombic, crystalline plates, which melt at 124° and boil at 322° ; this ether is 
freely soluble in alcohol, naphtha, and water. The corresponding ethylic oxalic 
ether is a colourless oily liquid, boiling at 363°, and but little, if at all, soluble 
in water. It was on this difference in the appearance of the two ethers that I 
at first had some idea of basing a test; but after making many trials, I have 
come to the conclusion that the difference is not available in any way, for methyl- 
oxalic ether, although crystalline under ordinary circumstances, does not crys¬ 
tallize in the presence of ethyl-oxalic ether, and both ethers are necessarily pre¬ 
sent in the distillate on submitting methylated spirit to the action of oxalic acid 
and distilling. The next trials were upon the difference in their respective solu¬ 
bilities ; it occurred to me that if ethylic-oxalic ether was insoluble in water and 
methylic-oxalic ether perfectly soluble, a method of separating and proving the 
presence of the latter might be based on its solubility. The mixed ethers could 
have been washed with pure water, the ethyl-oxalic ether allowed to settle, and 
the perfectly clear watery solution of methyl-oxalic ether poured off and tested 
with ammonia, when the formation of oxamide would indisputably have proved 
its presence ; but, unfortunately for this theory, I find that the ethyl-oxalic 
ether is sufficiently soluble in water to throw down a very decided precipitate of 
oxamide on the addition of ammonia, so that no reliance whatever can be placed 
upon this method of proceeding. 
The ethers having failed, I next tried the action of various salts and reagents 
generally ; after numbers of trials, many of them with no particular results, I 
resolved to see what effect a “ photographic intensifying solution ” would have, 
composed of biniodide of mercury dissolved in a solution of iodide of potassium, 
and to which along time before had been added some solution of potash, in order 
