AfeRICULTURAL MUSEUM 111 



half an ounce of nitrous acid, of the strength commonly 

 sold by the name oii^/JKi /b?/i.s-, (that is, the pure acid 

 diluted with about foiu- times its weight of water), aud 

 half an ounce of muriatic acid, sold by the name of spirit 

 of salt. Place the vessel in a sand-heat ; or, if you have 

 none, an iron pot or hre-shovelj with sand, may be put 

 over a common fire, and the matrass or phial set in it, 

 itaise a moderate heat, an effervescence will take place, 

 for the most part ; when this ceases, increase the heat un- 

 til it is renewed, and so proceed until the liquor boils, 

 ^vhichis also to be done if no effervescence takes place ; 

 boil them together for a quarter of an hour. 



Remove the vessel from the fire, and let it cool, then 

 pour into it two ounces of water, shake them together, 

 and let them stand tiil the liquor is clear ; pour the clear 

 liquor into a bason where it may be preserved. 



Add to the residuum a fresh half ounce of each of the 

 (kcids, and proceed again in the same manner, mixing the 

 clear liquor with that procured by the first process. 



The same operation is to be repeated, until the fresh 

 acids acquire no tinge of blue or green. 



Dissolve half a pound of mild fixed vegetable alkali, 

 commoni}' sold by the name of salt of tartar, in a quart of 

 water. Purify tlie solution, either by filtration, or by let- 

 ting the impurities subside and decanting the liquoi- clear 

 into a glass vessel. Pour the solution of the alkali slow- 

 ly into the bason containing the lluid procured by the 

 iormer processes, until the whole matter be precipita 

 ted from the acids. 



Add, by a little at a time, as much vitriolic acid, conv- 

 monly sold by the name of oil of vitriol, as will re dissoh*c 

 the whole, or only leave a white powder ; if there should 

 be any such powder, which is seldom the case, it must be 

 separated by filtration. 



Having the liquor in the bason novt' clear, put into it 

 a piece of iron, bright and free from rust, and at least an 

 ounce in weight, and leave theyii together for twenty 

 four hours; the copper will be found precipitated, prin- 



