144 ON THE WORKS AND CHARACTER 



his writings we shall learn that his mind was tuned to 

 great things. 



The greater part of Smithson's work was in analytical 

 chemistry. He discovered several tests, the most important 

 of which is the blow-pipe test for sulphur by reducing its 

 compounds on charcoal with carbdnate of sodium, and ob- 

 serving the stain on silver when the fused mass is laid upon 

 it in a drop of water (p. 66). In the paper " On the Detec- 

 tion of very Minute Quantities of Arsenic and Mercury," 

 (p. 75,) two very good tests for these elements are given, 

 especially that for the first : 



u If arsenic, or any of its compounds, is fused with nitrate of potash, 

 arseniate of potash is produced, of which the solution affords a brick-red 

 precipitate with nitrate of silver." 



The paper on page 82 gives a systematic course for distin- 

 guishing the mineral acids. On page 82 a flame-test is 

 given for strontium, which is perhaps the earliest applica- 

 tion of colored flames in analytical chemistry. In the 

 paper, page 94, "On some Compounds of Fluorine," the 

 method of detecting this element is described, and a very 

 neat form of apparatus given. The latter is peculiarly con- 

 venient in that the etching of glass and the change of color 

 of logwood paper may be simultaneously observed. 



A glance through his papers will show how much of his 

 work was actual analysis. Owing to the great improve- 

 ments in analytical chemistry since his day, his quantitative 

 results are of little value to us. This is not true, though, 

 of the qualitative work. The composition of the so-called 

 Tabasheer (hydrous silica), of the Egyptian colors, the pres- 

 ence of some carbonate in certain calami nes, as well as other 

 of his results, have a permanent value. "We are apt to 

 overlook them because they are become so obvious and ele- 

 mentary. 



Connected with and occasioned by certain of his analyses 

 are some considerations on the laws of the chemical compo- 

 sition of bodies. These, though erroneous, are the greatest 

 of his scientific attempts. They are found on page 27, 

 " Observations " appended to the paper on calamines. 

 These were published in 1802. A further development of 

 his views is found in the paper, page 34, " On the Compo- 

 sition of a Compound Sulphuret from Huel Boys," pub- 

 lished in 1808. His idea was that the weights of the prox- 

 imate constituents of any complex compound bore a simple 

 relation to one another. His experiments lead him to infer 

 that sulphate of zinc is composed of equal weights of ZnO 

 and SO 3 . This, though very nearly, is not accurately true; so 



