CHLORIDE OF AMMONIUM IN CHEMISTRY. 
83 
oxygen and chlorine is to the atomic weight of chlorine as 
the increase in weight to the amount of chlorine in the mass 
treated with sal-ammoniac; but from this amount of chlo- 
rine that of the alkaline metal can be obtained, and also that 
of the titanic acid. 
This determination can be checked in a very simple man- 
ner by treating the mass calcined with chloride of ammoni- 
um with water, which dissolves the alkaline chloride, the 
amount which can be determined by evaporation, while 
the titanic acid remains undissolved. 
It resulted from the experiments made on this subject, 
that the potash salt dried at 212° has the formula KO,6T O 2 
-f- 3HO, and the soda salt 2NaO, 9Ti0 2 + 5HO. The first 
forms a powder, which appears perfectly crystalline under 
the microscope, and consists of vitreous fragments. 
Sulphates. — The alkaline sulphates are completely decom- 
posed on ignition with chloride of ammonium into alkaline 
chlorides, from the weight of which the amount of the sul- 
phate can be accurately estimated. Sulphate of baryta is 
likewise decomposed by chloride of ammonium ; but it is 
almost impossible to render the decomposition complete, 
because the chloride of barium formed melts, and so pro- 
tects the undecomposed sulphate of baryta from further de- 
composition. Sulphate of magnesia is not decomposed by 
chloride of ammonium. 
Seleniates.— Seleniate of baryta is converted, on calcina- 
tion with chloride of ammonium, into a mixture of selenite 
of baryta and chloride of barium, which is coloured brown 
by free selenium. 
Alumina Compounds. — Calcined alumina, rubbed to a 
fine powder, is for the greater part volatilized by treatment 
with sal-ammoniac. A small portion, however, of coarser 
nature, most tenaciously resists the action of the chloride of 
ammonium ; and the alumina finally acquires, by the long 
ignition, such a state of density that it cannot be further de- 
composed by chloride of ammonium. Sulphate of alumi- 
