164 Dr. Dalton on the Constitution of the Atmosphere, 



series of experiments on the alkaline sulphurets, the chief ob- 

 ject of which is to ascertain the state of the alkali in the sul- 

 phuret, whether it is that of a metal or of an oxide. After 

 many experiments on the sulphurets of potash, soda, and 

 lime in the dry way, and one on sulphuret of lime in the humid 

 way, the author sums up, and notwithstanding his leaning to 

 the opinion that the alkalies exist in sulphurets in the state 

 of metals, he is obliged at last to acknowledge " that it is pro- 

 bable, hit 7iot yet demonstrated, that in all the sulphurets 

 formed by means of the alkaline oxides by a red heat, these 

 last lose their oxygen, and are united to sulphur in the metallic 

 state as is the case with the other metals." Gay-Lussac, in 

 the sequel of the same volume, page 322, in a memoir, ani- 

 madverts on the before-cited paragraph; and allowing that 

 sulphuric acid is formed when a sulphuret of potash made by 

 a red heat is dissolved in water, he contends, according to a 

 suggestion of BerthoUet, that the acid is formed in the instant 

 of solution from the reciprocal action of the sulphuret .and 

 the water, rather than from the oxygen of the potash and 

 sulphur. This opinion is countenanced by several combina- 

 tions of a similar nature, which he has adduced, and which 

 are worth the attention of chemists. 



Without adverting at present to my own experiments, I may 

 observe that Sir JohnHerschel,in an essay in the first volume 

 of the Edinburgh Philosophical Journal, 1819, was the first 

 writer who published an atomic view of the class of salts called 

 sulphuretted sulphites, or hyposulphites, that accorded with 

 what I had long entertained and demonstrated by reiterated 

 and decisive experiments*. In the above-mentioned essay 

 he showed clearly that the hyposulphurous acid is composed 

 of two atoms of sulphur and two of oxygen, which united to 

 one atom of base, as potash or lime, compose an atom of hy- 

 posulphite. The formation of thojie of lime, potash, soda, 

 barytes, and some metallic oxides is more particularly ex- 

 plained. A saturated solution of hyposulphite of lime at 50° 

 he found to be 1 '30 specific gravity f . 



In the 14th volume oi tXiQAnnales deChimie et de Physique, 

 Gay-Lussac has given the principal results of HerscheFs 

 essays on the hyposulphurous acid with some judicious re- 

 marks, but he leaves the subject as one requiring further in- 

 vestigation. 



♦ See New System of Chemical Philosophy, vol. ii. Preface, and p. 105. 



t Dr. Thomson, in a paper on the compounds of chromium in the Trans- 

 actions .of the Royal Society for 1826, disputes the accuracy of this con- 

 stitution of hyposulphuroua acid. 1 have never had any doubt concerning 

 it since 1815. 



