When pounded lime and sulphur are mixed together, and heated in a crucible scarcely any union takes place; the sulphur sublimes or burns away and leaves the lime unaltered. If for lime we substitute carbonate of lime, it also remains unaltered. But if hydrate of lime and sulphur are heated together in equal weights, the hydrate is decomposed, and the lime unites to a portion of the sulphur, whilst the excess of sulphur sublimes or burns and escapes at a low red heat. The residue, about 60 per cent. of the original weight, is a yellowish white powder, composed of sulphur and lime. If this be again treated with sulphur and heated, it undergoes no material change; the last sulphur entirely escaping, leaves the sulphuret unaltered, and hence shews that it must be a true chemical compound. Now if 32 parts hydrate of lime, which consist of 24 lime and 8 water, be mixed with 32 sulphur and heated as above, they will yield 38 parts sulphuret, which must be composed of 24 lime and 14 sulphur, or sulphur and water; but it appears from the analysis hereafter to be given, that the whole of this last part is sulphur; therefore the compound is formed of 1 atom of lime, and 1 of sulphur, and is the _protosulphuret_ of lime. When 32 parts of common hydrate of lime and 56 sulphur, are boiled together in 1000 parts water for half an hour, or more, occasionally adding water to supply the waste, a fine yellow liquid is obtained, with a few grains of residuum containing both lime and sulphur nearly in the original proportion with a few grains of alumine. This liquid of course contains in solution, a combination of 1 atom of lime, or perhaps hydrate of lime, and 4 atoms of sulphur; and may therefore be called a _quadrisulphuret_ of lime. If more sulphur or lime than the above proportion be used, the surplus will remain in the residuum uncombined, shewing that by this process no other than a quadrisulphuret can be formed. A similar solution may be obtained in cold water by frequent agitation; but it is much slower in producing the effect. The strength of liquid quadrisulphuret depends upon the relative quantity of the ingredients. I have boiled it down till the water was only 5 times the other materials, which appears to be its maximum strength in the common temperature; its specific gravity was 1.146; but in general I have used it of less than 1.07 density. It may be proper to remark here that I find the decimals multiplied by 4 express very nearly the number of grains of lime in 1000 grains measures of the solution, and multiplied by 9 those of the sulphur; on this account a solution of the sp. gravity 1.06 facilitates the calculations, as 100 measures of it contain 2.4 grains of lime, and 5.4 or 5.6 of sulphur nearly.