338 SALTS-SULPHITES. 



SULPHITE OF STRONTIA. 



This salt is most easily formed, by mingling an alkaline sulphite 

 with a solution of the earth in an acid, when there will be a precipit- 

 ate of the sulphite of strontia, which is insoluble. 



SULPHITE OF MAGNESIA. 



1. Formed also by diffusing the carbonate in water, and passing 

 sulphurous acid gas through it. 



2. Insoluble till there is an excess of the acid ; gives crystals which 

 are flattened tetrahedra. 



3. Requires 20 parts of cold water for solution. 



4. Taste sweetish and earthy. 



SULPHITE OF ALUMINA. 



1. A white soft insoluble powder. 



2. Soluble in an excess of acid. 



SULPHITE OF POTASSA. 



1. Formed with ease, from a saturated solution of the carbonate. 



2. Crystals, long rhomboidal plates or divergent needles. 



3. Soluble in water, 1 part at 60, in less at 212. 



4. Composition, 43.5 acid, 54.5 potassa, 2 water; (Thomson) by 

 theory, 1 potassa, 48; 1 acid, 32 = 80, its equivalent. 



5. Slightly effloresces in air, and becomes sulphate; decrepitates. 



6. Decomposed by baryta and lime. 



SULPHITE OF SODA. 



1. Crystals, tetrahedral prisms, with dihedral summits. 



2. Dissolves in 4 parts of cold water, in less than 1 at. 2 12. 



3. Effloresces ; suffers aqueous fusion, and is decomposed at last 

 by heat. 



4. Composition, soda 1 proportion 32, acid 32, water 9=108; 

 = 172 for the equivalent. 



5. Potash decomposes it, attracting its base. 



SULPHITE OF AMMONIA. 



1. Crystals, six sided prisms, terminated by pyramids with the 

 snme number of sides, or rhomboidal prisms with trihedral summits. 



2. Soluble in 1 part of cold water, and in less at 212. 



3. Deliquesces, and becomes converted into a dry sulphate. 



4. Fused and volatilized by heat. 



5. Composition, 17 ammonia, 32 acid, for the anhydrous salt, 

 giving 49 for its equivalent ; and when crystallized, 2 equivalents 

 of the salt, = 98 -f 1 of water, 9=107 by theory. Brande. 



