^4 ^^' Brande on the State in which Alcohol exists 



The acetate of lead and the subnitrate of tin produce the 

 desired effect of separating the colouring and acid matters, in 

 the greater number of instances, but they are less rapid and 

 perfect in their action, and not so generally applicable as the 

 subacetate of lead,* which is the substance that I commonly 

 employed. 



The following experiment was made with a view to ascer- 

 tain the effect of this salt. 



Twenty measures of alcohol, specific gravity ,82500, were 

 mixed with eighty measures of distilled water coloured with 

 log wood, and rendered slightly acid by supertartrate of pot- 

 ash. Four measures of a concentrated solution of the subace- 

 tate of lead were added to this mixture, and the whole poured 

 upon a filter. A precipitate was thus collected of a deep purple 

 colour, which appeared to consist of oxide of lead combined 

 with tartaric acid and the colouring-extractive matter. 



The filtered liquor was perfectly transparent and colour- 

 less, and afforded, on the addition of subcarbonate of potash, 

 19,5 measures of alcohol, -f 



• The effect of this salt upon colouring matter,, was first pointed out to me by Mr. 

 E. M. Noble of Chelsea. 



f Pure subcarbonate of potash, obtained by igniting the carbonate, was employed 

 in these experiments, I found that about 19,5 parts of alcohol were separated in the 

 .course of four hours, by the addition of 50 parts of the subcarbonate to a mixture of 

 20 parts of alcohol by measure with 80 of distilled water, and that no further sepa- 

 ration took place. The alcohol is always slightly alkaline, probably from containing 

 a small portion of the solution of the subcarbonate, or of pure soda, but as this did 

 not interfere with the object of the experiment, it was not particularly attended to. 



When the subcarbonate was added to a mixture of four parts by measure of alcohol 

 with 96 of water, no separation was effected.— -A mixture containing 8 per cent, of 

 alcohol afforded about 7 parts— one containing 16 per cent, about 15,5, and where 

 the proportion of alcohol exceeded \6 per cent, the quantity, indicated by the action. 



