1825.] . Scientific Notices^-^Chemistr^, 231 



*' Some sea sand was heated red hot for half an hour in a 

 crucible, and then poured out on to a copper-plate, and left to 

 cool ; when cold, a portion of it (about 12 grains) was put into 

 a clean glass tube ; another equal portion was put into the 

 palm of the hand, and looked at for a few moments, being 

 moved about by a finger, and then introduced by platina foil 

 into another tube, care being taken to transfer no animal sub- 

 stance but what had adhered to the grains of sand : the first 

 tube when heated yielded no signs of ammonia to turmeric 

 paper, the second a very decided portion. 



" As a precaution, with regard to adhering dirt, the tubes 

 used in precise experiments were not cleaned with a cloth, or 

 tow, but were made from new tube, the tube being previously 

 heated red hot, and air then drawn through it ; and no zinc or 

 potash was used in these experiments, except such as had been 

 previously tried by having portions heated in a tube to ascertain 

 whether when alone they gave ammonia. 



^' It was then thought probable that the alkali might contain 

 a minute quantity of some nitrous compound, or of a cyanide, 

 introduced during its preparation. A carbonate of potash was 

 therefore prepared from pure tartar, rendered caustic by lime 

 calcined immediately preceding its use, the caustic solution 

 separated by decantation from the carbonate of lime, not allowed 

 to touch a filter or any thing else animal or vegetable, and 

 boiled down in clean flasks ; but the potash thus obtained^ 

 though it yielded no appearance of ammonia when heated alone, 

 always gave it when heated with zinc. 



" The water used in these experiments was distilled, and in 

 cases where it was thought necessary was distilled a second, 

 and even a third time. The experiments of Sir Humphry Davy 

 show how tenaciously small portions of azote are held by 

 water, and that, in certain circumstances, the azute may pro- 

 duce ammonia. I am not satisfied that I have been able to 

 avoid this source of error. 



"At last, to avoid every possible source of impurity in the 

 potash, a portion of that alkali was prepared from potassium ; 

 and every precaution taken that could be devised for the ex- 

 clusion of azote ; yet, when a lamp was applied to the potash 

 and zinc, the alkali no sooner melted down and mingled with 

 the metal, than ammonia was developed ; which rendered the 

 turmeric paper brown, the original yellow re-appearing by the 

 application of heat to the part. '' f 



*' Still anxious to obtain a potash which should be unexcep- 

 tionably free from any source of azote, I heated (says Mr. F.) a 

 portion of potash with zinc, endeavouring to exhaust anything 

 it might contain which could give rise to the formation of am- 

 monia : it was then dissolved in pure water, allowed to settle, 

 the clear portion poured ofi* and evaporated in a flask by boil- 



