Conversion op malt spirit into vine oar, §7^ 



VII. 



Extract of a Letter from Mr. Resal, Apothecary at Re- 

 rnirementy to Mr. Cad :r, Apothecary to the Emperor, ini 

 the Conversion of Malt Spirit into Vinegar, and on tht 

 Red Colour of Oil of liempseed *. 



I 



TAKE the liberty of imparting to you an observation Malt spirit 

 respecting the article of Mr. Hebert of Berlin, wiio.se pro- converted into 

 cess you could not verify without it. I communicated it to 

 Mr. Parmentiera twelvemonth ago, with several other notes, 

 part of which was inserted in the month of May, 1 806. One 

 of these was on the vinegar of brandy, which chance threw 

 in my way. I had mixed some malt spirit [alcoolde bierre) 

 vrith an equal quantity of water, and added to it some 

 beech charcoal. Bein£ set aside and forgotten, I w T as sur- 

 prised at the end of a twelvemonth to find it converted into 

 a very strong vinegar, and the unpleasant taste of the beer 

 still subsisting. 



With your permission I will add an observation respecting 

 the property of liquids to absorb different solar rays. 



It is known, that various substances absorb this or that Oil of hemp- 

 luminous ray, but I do not believe that any one has men- seed grows red 



*vi •» >* i ,. id the sun. 



tioned the property, that oil ot nempseed, cannabis sativa 



E.j has to absorb the red rays when they are direct only, and 

 to appear of a fine blood-red colour ; so that, being lighter 

 than rape or linseed oil, as it returns to the upper part of 

 the vessel it appears equally red, without changing the 

 colour of the oil it floats on. Its use in the arts, since it 

 offers more resistance to the air than linseed oil, and doea 

 not skin [ne se crispe pas] like it; and its mixture with 

 oils for the lamp being very common from its low price, 

 while it yields a thick smoke ; require a method of detect- 

 ing it. This that I have mentioned perhaps would answer, 

 and even show the effect of the solar rays on different sub- 

 stances. 



* Annates de Chimie, vol. LXIV, p. 961. 



T 2 Remarks 



