IS^ <^N AMMONIA. 



portion to each other, as determined by his own experiments, 

 Mr. Berthollet finds, that 100 parts by weight of ammonia 

 consist of 



Coinposition 

 of ;unn)oniacal 



81-13 nitrogen, 

 18*R7 hiv'ji-ogen. 



100. 



precaution in 

 »he use of 

 V'oltA's eudio- 

 meter- 



When oxigeii 

 and hidrogen 

 are fixed over 

 mercury, if the 



oxigen be m 

 excess, nitric 

 acid 6s oxide 

 of mercury 

 are forjned. 



Detonations 

 over water 

 preferred. 



The memoir of Mr. Berthollet concludes with some use- 

 ful practical directions for obtaining- accurate results by 

 A^olta's Eudiometer. The circumstance, which he finds to 

 be of most importance, is such an adjustment of tlie gasses 

 to each other, as will afford a pretty hirge residuum after 

 combustion. If the residuary gas be only one sixth of the 

 original mixture, air is extricated from the water, over which 

 the detonation is made, in such a quantity as to prove a 

 source of fallacy. When the residuum is one fourth, the 

 effect may be overlooked ; and, when it amounts to half the 

 volume of the original gasses, the uniformity of the results 

 show, that they are no longer influenced by the extrication 

 of air from the water. 



Comparing experiments on the detonation of hidrogen 

 and oxigen gasses over mercury, with similar ones over wa- 

 ter, Berthollet found, that they agree accuiately when the 

 hidrogen is in excess. But when the oxigen prevails, the 

 diminution is greater than it ought to be. -An experiment, 

 made expressly to elucidate this point, showed, that, under 

 these circumstances, the oxigen combines not only with the 

 nitrogen which is unavoidably mingled with it, but also with 

 the mercury. Two litres (upwards of 120 cubic inches) of 

 a mixture of hidrogen and oxigen gasses, with an excess of 

 the latter, were fired by forty successive explosions. Water 

 was formed ; and, beside this, an oxide of mercury in its 

 lowest stage of oxidation. The liquid was strongly acid ; 

 potash threw down a black oxide; and paper afterward im- 

 pregnated with the solution bu' ned as if dipped into a so- 

 lution of nitre. 



On the whole, Mr. Berthollet is disposed to expect 

 greater precision from detonations made over water, thaa 

 from thoae over mercury, especially when care is taken to 



have 



