Phosphorus and Sulphury &tc. 42^ 



iifpear to be composed of one proporlion of sulphur lo 

 thiee of oXvgen. I have endeavoured, in several trials by 

 ■common heat and by electricity, to combine sulphnreoui 

 acid i>as w'nn oxygen, so as to form a sulphuric acid free 

 tVom water, bul'witliout success ; and it is probable that 

 three proportions of oxygen cannot be combined with 

 bae proportion of sulphur, except by the intermedium of 

 water. jVJr. Daltou has supposed that there is a solid sul- 

 phuric acid formed by the action of sulphureous acid gas 

 upon nitrous acid gas. But I find, that when dried sul- 

 phureous acid gas and nitrous acid gas are mi.^ed together, 

 there is no action ; but bv introducing the vapour of water, 

 ihey form together a solid crystalline hydrat ; which whei-i, 

 thrown into water gives oflf nitrous gas, and forms a solu- 

 tion of sulphuric acid. 



I have referred, in the Philosophical Transactions, to ths 

 combination of chlorine and sulphur. I have been able to 

 form no compound of these bodies, which does not deposit 

 sulphur bv the action of water. VVhen sulphur is saturated 

 with chlorine, as ia Dr. Thomson's sulphuretted liquor, it 

 appears to contain, from my experiments, only 67 of chlo- 

 rine to 30 of sulphur. 



4, Somv geneful Observations. 



It is a fact vjorthy of notice, that phosphoric and sul- 

 phuric acids should contain the same quuntity of oxygen 

 to the same quantity of inflammable matter ; and yet that 

 the oxvgen should be combined in themj with such dif- 

 ferent degrees of affinity. Phosphorous acid has a great 

 tendency to unite with oxvocn, and absorbs it even from 

 water ; and sulphureous acid can only retain it when water 

 i'S present. 



The relation of water to the composition of many bodies 

 has already occupied the attention of some distinguished, 

 chemists, and is well worthy of being further studied : most 

 of the substance^ obtained bv |)recipitation from aqueouJ 

 Solutions are, J find, compounds of water. 



Thus zircona, n)HCTuesia, silica, when precipitated and 

 dried at 212^, still contain definite proportions of water. 

 And many of the substances which have been considered 

 as metallic oxides, that I have examined, obtained from 

 8f)lutions, agree in this respect; and their colours and other 

 properties are materially iullucnced by ibis combined water. 



I shall give an instance. The substance which has been 



called the white oxide of manganese is a compound of 



water and the protoxide of manganese, and when heated 



suongly, it gives ofTita water and beconics a dark olive yxidc. 



Dd4 It 



