HYPO-SULPHUROUS ACID. 339 



HYPO-SULPHUROUS ACID. HYPO-SULPHURIC ACID. 



HYPO-SULPHITES. HYPO-SULPHATES. 



Remarks. In the present advanced state of chemistry, the most 

 serious inconvenience encountered by the student, is found in the great 

 extent and variety of details. In a concise elementary work, it is im- 

 possible to present them all, and there seems to be no better course 

 than to omit, or to notice slightly the least important, and to enlarge 

 upon those of the opposite character, giving at the same time, sufficient 

 references to original sources of information. 



Were it not that it is desirable to preserve the chemical history of 

 bodies unbroken, and particularly to display the extent and precision 

 of definite and multiple proportions, I should hardly have thought it 

 best to say any thing of the preceding sulphites or of the acids and 

 their compounds which stand at the head of these remarks. 



HYPO-SULPHUROUS ACID. 



1. Composition. 1 proportion of oxygen, 8, and 1 of sulphur, 32 

 =40, for its equivalent. 



2. Preparation. Difficult to obtain and preserve in an isolated 

 state. It is done, 



(a.) By decomposing the dilute solution of hypo-sulphite of stron- 

 tia, by dilute sulphuric acid ; the earth is precipitated and the acid 

 liberated. 



(5.) By digesting sulphur in a solution of any sulphite, when an ad- 

 ditional proportion of sulphur is dissolved, and hypo-sulphurous acid 

 formed ; or by decomposing hydro-sulphuret of lime* or strontia, by a 

 stream of sulphurous acid gas, when there is an exchange of one pro- 

 portion of the oxygen of the sulphurous acid for one proportion of 

 the sulphur of the hydro-sulphuret, water being formed, and thus two 

 proportions of sulphur remain in union with one of oxygen. 



3. Properties. A transparent, colorless, inodorous acid ; decom- 

 posed spontaneously, sulphur precipitated, and sulphurous acid re- 

 mains. 



HYPO-SULPHITES, OR SULPHURETTED SULPHITES. 



1. Preparation. 



(a.) The hypo-sulphites of the alkalies and alkaline earths are best 

 obtained by passing a stream of sulphurous acid gas through a lixi- 

 vium of those bodies that has been boiled with sulphur ; the sulphurous 

 acid is converted into hypo-sulphurous, and the excess of sulphur pre- 

 cipitated. 



(6.) By boiling a sulphite with sulphur. 



(c.) By double decomposition ; an alkaline hypo-sulphite being 

 mixed with an acid solution of some other base. 



*Seep. 347. 



