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 carbonate of sodium, and ob- 

 servino- 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 : 



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

 ftrseniate 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 coufee 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 calamines, 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^. This,though very nearly, is not accurately true; so 



