86 
PROFESSOR W. RAMSAY AND OR. S. YOUNG 
‘ Berichte/ 1871, p. 780) ; by Bineau (‘ Annales,’ 67, p. 240); and by H. Bose (Pogg. 
Ann., 46, p. 363), that the vapour-density of ammonium carbamate is 13'0, correspond¬ 
ing to complete dissociation into 2NH 3 + C0 3 . It might, therefore, be expected to 
yield results somewhat analogous to those obtained with chloral hydrate. 
§ 34. Temperatures of Volatilization of Ammonium Carbamate. 
As it was impossible to coat the bulb of the thermometer in the usual way with 
this substance, a block of commercial carbamate was drilled with a hole, which the 
thermometer exactly fitted ; and it was then turned in a lathe to form a cylinder of 
convenient size. The following numbers refer, therefore, to commercial carbamate, or, 
as it is usually termed, carbonate of ammonia. The apparatus was the same as that 
employed for chloral hydrate. To ensure thorough condensation of the evolved gases, 
tubes containing pumice-stone, moistened with sulphuric acid, and stick-potash were 
interposed between the apparatus and the pump. The jacket was the vapour of 
boilinsr aniline. 
O 
The first series consisted of two readings, every care being taken to keep the 
pressure low. The pressures were 5 and 9 millims. respectively, and the temperatures 
62° and 64°. 
The second series gave the following numbers :— 
Pressure. 
Temperature. 
Pressure, 
Temperature. 
Pressure. 
Temperature 
millims. 
O 
millims. 
O 
millims. 
O 
100 
65-8 
145-5 
64-2 
130 
66'0 
115 
65-4 
162-0 
677 
210 
66-0 
130 
64-5 
156"0 
68-0 
202 
65-4 
139 
63-5 
144-0 
67'4 
200 
65"0 
145 
63-3 
130-0 
66-5 
From these experiments it will appear that, as in previous cases, pressure and 
temperature are independent of each other. The maximum temperature attained 
was 68°, although the temperature of the jacket was over 180°. The results are 
shown in Plate 1. 
§ 35. Ammonium Chloride, NH^Cl.—This substance has given rise to long discussions. 
The solution of ammonium chloride is known to dissociate on boiling, for ammonia is 
first evolved, and the residual liquid is acid (Fittig, ‘Annalen/ 128, p. 189). Its vapour 
density corresponds to a mixture of NH S and HC1 at 350° and atmospheric pressure 
(Deville and Troost, £ Comptes Bendus,’ 56, p. 895), and also at higher temperatures. 
Horstmann, from not very concordant results, concluded that its vapour-density is 
greater at 300° and a pressure of from 40 to 60 millims., than at 360° under normal 
pressure (‘ Berichte,’ 1869, p. 299). At 360° Deville found that on mixing the gases 
heat was evolved, necessarily implying some combination; Wanklyn, however, states 
