144 On the Formation of Ammon ia, $c. 



surprised to find that ammonia was still a result of the experi- 

 ment. This led to trials with different vegetable substances, 

 such as the proximate principles, acids, salts, c., all of which 

 yielded ammonia in greater or smaller quantity; and ultimately 

 it was found, that even several metals when treated in the same 

 way gave similar results ; a circumstance which appeared con- 

 siderably to simplify the experiment. 



The experiment may be made in its simplest form in the 

 following manner : Put a small piece of clean zinc foil into a 

 glass tube closed at one end, and about one-fourth of an inch in 

 diameter 5 drop a piece of potash into the tube over the zinc ; 

 introduce a slip of turmeric paper slightly moistened at the 

 extremity with pure water, retaining it in the tube in such a 

 position that the wetted portion may be about 2 inches from 

 the potash ; then holding the tube in an inclined position, apply 

 the flame of a spirit-lamp, so as to melt the potash that it may 

 run down upon the zinc, and heat the two whilst in contact, 

 taking care not to cause such ebullition as to drive up the pot- 

 ash ; in a second or two the turmeric paper will be reddened 

 at the moistened extremity, provided that part of the tube has 

 not been heated. On removing the turmeric paper and laying 

 the reddened portion upon the hot part of the tube, the ori- 

 ginal yellow tint will be restored : from which it may be con- 

 cluded that ammonia has been formed ; a result confirmed by 

 other modes of examination to be hereafter mentioned. 



The first source of nitrogen which suggested itself was the 

 atmosphere : the experiment was therefore repeated, very care- 

 fully, in hydrogen gas, but the same results were obtained. 



The next opinion entertained was, that the potash might 

 have been touched accidentally by animal or other substances, 

 which had adhered to it in sufficient quantity to produce the 

 ammonia : the alkali was therefore heated red-hot, as a pre- 

 paratory step, and afterwards allowed to touch nothing but 

 clean glass or metals ; but still the same effects were produced. 

 The zinc used was selected from a compact piece of foil, was 

 well rubbed with tow dipped in alkali, washed in alkaline solu- 

 tion, afterwards boiled repeatedly in distilled water, and dried, 

 not by wiping, but in a hot atmosphere ; and yet the same pro- 

 ducts were obtained. 



All these precautions, with regard to impurity from finger- 



