44 Mr Johnston on tfie Cri/stalli^cd 



of chlorine, and, by cautious evaporation and heating to redness, 

 the metal may be obtained in the state of antimonious acid. By 

 the most careful procedure, however, it is difficult to obtain it 

 entirely free from a trace of chloride or oxide, which causes a 

 small loss when -heated to redness. By this process I ob- 

 tained in three experiments 75.93, 76.506, 75.98, for the 

 per-centage of metal. 3d, Gently heated in an atmosphere 

 of sulphuretted hydrogen, muriatic acid is disengaged, a little 

 chloride of antimony is carried over with it, and the black 

 sulphuret remains. By a cautious application of the heat so 

 as to prolong the process for two or three hours, the quan- 

 tity of chloride volatilized may be very much diminished, so 

 as to reduce the loss below a quarter per cent. Should any 

 notable quantity of white fumes make their escape, they may be 

 decomposed by causing them to pass through water, and the 

 antimony afterwards collected in the state of sulphuret. In two 

 experiments, I obtained by this method 76.558 and 76.6 for the 

 amount of antimony. In these results I have most confidence ; 

 in both, however, there was a trifling loss, so that they ought to 

 be rather under the truth. 



I endeavoured to determine the oxygen directly by heating 

 the salt to redness with charcoal in a glass tube and collecting 

 the carbonic acid evolved, but the approximation obtained was 

 very rude. Reckoning the loss as oxygen, therefore, we have 

 for the composition of the salt, — 



Chlorine = 11.32 = 2.55 atoms. 



Antimony = 76.6 = 9.498 



Oxygen = 12.08 = 12.08 — 



100 



Where the number of atoms of antimony is to ihis sum of those 

 of chlorine and oxygen as 2 to 3.08, very nearly the relation 

 which the electro-negative element bears to the metal in the 

 oxide and first chloride of antimony. 



The atomic constitution which agrees most nearly with these 

 numbers is the following : — 



