OF JAMES SMITIISON. 147 



of equilibrium induced by heat between the constituent 

 parts of a body." 



'' Why is the change of quality limited to the surface ; how has been 

 produced the central cavity ; what has forced away the matter which 

 occupied it ? A new element has been received from without, one which 

 existed in the matter has been parted with in a state of vapor. This double 

 action may probably be inferred wherever a matter presents this species of 

 vegetation," (p. 100.) 



As the story of his analysis of a tear indicates, he was an 

 exceedingly nice manipulator. He was one of the very first 

 who commenced the cardinal practice of modern analytical 

 chemistry, the use of delicate methods and small quantities 

 of material. His quantitative determinations were usually 

 made with about a gramme, and his qualitative determina- 

 tions often with almost invisible bits. In the examination of 

 the "Native Compound of Sulphuret of Lead and Arsenic" 

 (binnite of Naumann) from Upper Valois, his " trials were 

 made with particles little more than visible." On page 95 

 he says :' "A very minute fragment of fluor spar is fastened 

 by means of clay to the end of a platina wire nearly as fine 

 as a hair, which is the size I now employ even with fluxes." 

 We have before noticed the neat and simple apparatus (p. 

 97) for the detection of fluorine. On page 86 a method of 

 making and using thin clay plates is given, which might, 

 at the present time, be advantageously employed in blow- 

 pipe work, especially if the} 7 were made from a pure kaoline. 

 The paper on the " Method of Fixing Particles on the Sap- 

 pare " (fibres of cyanite) contains repeated instances of his 

 delicacy and neatness. 



Smithson's contributions to mineralogy consists princi- 

 pally in the discovery of several new species. Native red 

 lead was first examined by him and its having been derived 

 from galena demonstrated. He also first observed chloride 

 of potassium, in a native state from Vesuvius. He attributed 

 its presence in lava to sublimation. The native compound 

 of sulphuret of lead and arsenic is the rhombic mineral 

 binnite (of Naumann), as is recognized by its locality, chem- 

 ical composition, hardness and cleavage. He also described 

 a native compound of sulphate of barium and fluoride of cal- 

 cium from Derbyshire. Naumann (Min., 9te Aufl., p. 261, 

 Anmerkung 3) thinks, as is correct, that this is only a mix- 

 ture and not a true species. 



The crystallographical observations of Smithson are of 

 rather a rough character, owing perhaps to his instruments. 

 They refer to the forms of electric calamine, of bournonite 

 (the compound sulphuret from Huel Boys) and of ice. The 



