82 On definite Proportions. 



experiments, as Davy had conjectured that sulphur and 

 phosphorus contained unknown metallic bodies, united 

 with small portions of hydrogen and oxygen, and bore 

 nearly the same relations to these bases as the re?ins do to 

 carbon. He has indeed advanced so nianv ingenious ar- 

 guments in favonr of this hypothesis, that it can scarcely be 

 called altogether void of probability : at the same time I 

 cannot consider it as perfectlv consistent v^ith my experi- 

 ments : for, when I have used sulphur that was perfectly 

 dry, and had been enoue'b melted, I have never been able to 

 discover any trace of sulphureted hydrogen, or of aqueous 

 vapour, emitted during the combination of metals with sul- 

 phur. But I have often observed, that when I have em- 

 ployed washed and apparently well dried or rapidly melted 

 flowers of sulphur, no moistuie made its appearance while 

 the sulphur remained melted over the metal ; but when, at 

 the moment of cambination, the beat became more intense, 

 a small quantitv of sulphureted hydrogen has been evolved, 

 and aqueous vapour has been deposited on the gl.^ss, a little 

 sooner than the sulphur \Abich was sublimed at the same 

 time. Consequently, either the- oxygen and hydrogen 

 found by Davy depended only on the accidental presence of 

 moisture, or they enter, together with the unknown basis, 

 into combination with the metals; which is much more 

 contrary to analogy than the parallel between sulphur and 

 the resins is supported by analogv. We shall also see that 

 these substances, if they are present in sulphur, must be 

 retained when it combines with oxygen to form an acid. 

 Sulphur and phosphorus, and, as 1 suspect, boraeium, 

 fluorium, and carboti, give, with the metals, combinations 

 tjf a very different character from those of the metals with 

 each other. They cannot be alloyed in all possible pro- 

 porlioiis with metals, but are limited either to a single 

 proportion, or to a few definite degrees, between whi'eh 

 there are no intermediate steps. 



A. Sulphuric Acid. 



In order to avoid all mechanical adherence of moisture, 

 f employed in this invcitigation the sulphuret of lead. 



1.) Ten gramiT)es of finely powdered sulphuret of lead 

 were digested with aqua regia in a weighed glass flask, as 

 Jong as any oxygenization was perceptible ; and the mass 

 was then dried and ignited : it weighed li'-65gr. It was 

 afterwards digested with water, to which a little concen- 

 trated vinegar had been added ; but the liquid acquired no 

 sweet taste, and contained no lead. Consequently the sul- 

 phur 



