1793' literary inteU'tgehce . 73 



particularly water, to their natural state, by simple admix- 

 ture of pounded charcoal. 



It appears by a late London newspaper, that Mr 

 Lovitz, although probably ignorant of the fact, was not 

 the first discoverer of the curious operation of charcoal 

 on water ; for in 9 paragraph of the said newspaper, (its 

 date I have forgot, though probably sometime in December 

 1792.) I read, that a steward of the navy had discovered 

 last war a mode of preserving water sweet for any length 

 of time, by mereiy burning the inner surface of the cafcs, 

 so as to produce a coating of charcoal a few lines thick. 

 The above, which your correspondent quotes from me- 

 mory, is exactly the principle of Mr L jvitz, and merits the 

 attention of your victualling office*. 



He has lately discovered a mode of chrystalizing the 

 caustic vegetable alkali, per se, which difsolves so quickly 

 when mixed with snow, and both become liquid so instan- 

 taneouly, as to produce a degree of cold which a man 

 versed in these experiments, could have scarcely suppos- 

 ed pofsible, and which certainly does never obtain natu- 

 rally in any part of the habitable globe. The ulm.ost 

 cold Dr Guthrie of this city was able to produce in 

 1785, by frigorific mixtures of nitrous acid and snow, 

 when aided by a natural cold of twenty degrees below 

 o of Reaumeur, was only thirty-six, that is only four de- 

 grees more than necefsary to congeal mercury, in all its 

 degrees of purity or adulteratiojt, which he found made 

 not the It-ast difference with regard to its freezing point, 

 uniform. ly at thirty-two of Reaumeur. But Mr Lovitz, 



* Charcoal, from many late experiments, appears to be one of the 

 most powerful chemical agents yet known, whose eftects have never 

 yet been sufficiently attended to ; it is therefore recommended as a 

 very proper object for experimental investigation by young mea 

 who are keen in the active pursuit of useful knowledge. Edit, 



vor. .\vi,> ^ , -^ 



