214? PRACTICAL CHEMISTRY. 



Explanation. bably thefe are feeds buried in f he earth for many ages, which 

 yet remain alive, but do not p<ow until expofed to the ftimuli 

 of air, water calorific, and lifelefs animal, or vegetable 

 matter. 



(To be concluded in our next.) 



XII. 



Letter from Mr. Accum, re/peeling an Error ftated to exift in 

 his Practical Chemifiry. 



To Mr. NICHOLSON. 



SIR, Compton- Street, Soho^ 



Feb.\6, 1805. 



Omiffion ftated ^^ * F * C. cenfures me in your Journal, No. 38, page 

 to be made in 105, of not having given in my book on Practical Chemiftry 

 " The means of preparing either nitric acid, or nitrate ofpotqfh, 

 or rather having ftated them by implication, as incapable of being- 

 produced by art." The fidelity with which you have laid his 

 remarks before the public, encou. .ges me to hope, that with 

 equal impartiality you will allow me to appear before the fame 

 tribunal, in order to plead to this accufation not guilty. 

 For the method of obtaining nifric acid from its constituent 

 principles, W. F. C. may read in the Vol. I. page 211. 



In qrder to let the judicious readers wild are not in poffeflion 

 of the work, judge for themfelves, I beg leave to lay before 

 them the method there pointed out, which literally runs thus : 

 Paflage where " Ta/x ' e a barometer tube, thediameter of -which is about ^ part 



the fuppofed of an inch. Shut one of its extremities with a cork, through the 

 middle of ivhich paffes a fmall win with a ball of metal at each 

 end. Fill the tube irith mercury and invert it into a bafon of this 

 fluid. Throw up into this tube as much of a mixture of 12 parts 

 of nitrogen gas, and 87 parts of oxigen gas as will fdl 3 inches. 

 Through this gas by means of the ivire in the cork pafs a number 

 of eleclric /parks ; the volume of the gas gradually diminifiies, 

 and in its place will be found nitrous acid." * 



Accum's che- 

 mifiry 



omiffion is 

 found. 



* Nitrous acid does not differ from nitric acid, in compofition, but 

 merely by the admixture of nitrous gas. See the book under co n . 

 fideration, Vol. II. p. 288. 



It 



