534 
DETECTION OF METHYLIC ALCOHOL. 
of reading over tlieir policies carefully, in order to understand clearly the nature 
of the agreement contained in them, so that there may be no risk of loss or 
litigation should a fire occur. 
Yours respectfully, 
M. Carteeghe. 
172, New Bond Street , W. 
DETECTION OE METHYLIC ALCOHOL IN PRESENCE OF 
ETLIYLIC ALCOHOL AND VOLATILE OIL. 
BY JOHN T. MILLER. 
Of the tests for methylic alcohol hitherto proposed, none can be said to be 
altogether satisfactory. No great reliance can be placed on the indications of 
the potash test; methylated spirit may without much difficulty be so far 
“ cleaned” as to be only slightly discoloured by caustic potash ; and Eschwege’s 
purified naphtha is merely tinged yellow by it after the lapse of some hours. 
Better results are obtainable by the use of sulphuric acid. When, for instance, 
a small quantity of the purified naphtha is mixed with an equal bulk of strong, 
colourless sulphuric acid contained in a test-tube, no immediate development of 
colour occurs ; but upon treating the mixture—not however to boiling—it be¬ 
comes of a deep red-brown colour. If pure spirit of wine is subjected to the 
same treatment, it remains colourless; but ordinary rectified spirit, owing to the 
trace of fusel oil it contains, shows a slight tinge of colour ; while rectified 
spirit mixed with five or six per cent, of Eschwege’s naphtha takes a light amber 
tint. Pure ether similarly treated continues colourless, but the methylated 
article turns brown. The necessity of removing all traces of volatile oil from 
the spirit to be examined is however a serious obstacle to the general use of this 
test. The above are not, properly speaking, tests for methylic alcohol, as the 
reactions are not due to that substance, but to other matters with which it is 
usually associated in the commercial wood-spirit; and in this respect they agree 
with the mercurial test of Mr. E. Reynolds, the action of which, according to 
that chemist, is owing to acetone. 
The method which, after an extended trial, I have found to give good results, 
and to be capable of very general application, is based on the difference of the 
products of the oxidation, under certain conditions, of e thy lie and methylic 
alcohol: the former yielding principally water, aldehyde, and acetic acid, with 
only traces of formic acid; the latter giving, together with other products, formic 
acid in comparatively large quantity. The following experiments demonstrate 
this :— 
Put into a small distilling apparatus 60 grains of powdered bichromate of 
potash, and pour upon it 1 ounce of water and 90 grains of sulphuric acid, sp. 
gr. 1-845, then add 1 fluid drachm of rectified spirit. Let the mixture stand 
fifteen minutes, and distil 1 fluid ounce. Neutralize the distillate with carbo¬ 
nate of soda, boil it down nearly to dryness, add water to make up the quantity 
4 fluid drachms, and render the solution sufficiently acid to redden litmus paper 
by the addition of a drop or so of acetic acid, then pour it in equal portions 
into two perfectly clean one-ounce test-tubes. To one portion add 1 grain of 
nitrate of silver dissolved in half a fluid drachm of water, heat to boiling, and 
boil gently for about two minutes. The mixture darkens slightly but does not 
lose its transparency, and if the tube is filled with water and set aside, a minute 
dark precipitate slowly subsides, leaving the glass clear and free from brown 
deposit. To the other portion of the solution half a fluid drachm of acetic 
acid, and a few drops of solution of nitrate of suboxide of mercury, are to be 
