JAMES SMITHSON AND HIS BEQUEST. 57 



it ; borax more difficultly. It melted, also, at the blow-pipe, where the 

 ashes of the coal happened to touch it, or when rubbed over with calca- 

 reous earth ; and this appears to be the only property in which it differs 

 materially from flint. This fusibility with calcareous earth, and its con- 

 tracting and hardening in the fire, might lead us to suspect an admixture 

 of argillaceous earth j but no traces of that earth were discovered by the 

 usual process with vitriolic acid. 



"The experiments from which these general results are extracted 

 were made on the finest tabasheer that could be purchased at Hydrabad. 

 Several other specimens were examined, and all the genuine sorts were 

 found to consist of the same earth. That which was taken immediately 

 from the cane became black in the fire from some admixture of vegeta- 

 ble matter^ but as soon as the blackness disappeared it was in all re 

 spects similar to the foregoing, so that the tabasheer of Hydrabad may 

 be presumed to have suflered a degree of calcination before its exposure 

 to sale. 



"That a siliceous earth exists in vegetables is evident from their 

 ashes. Mr. Macie obtained a small portion of this earth from the ashes 

 of charcoal, but found it far more abundant in those of the bamboo 

 cane. He mentions a singular circumstance respecting this vegetable 

 which occurred after his experiments were finished : 



"A green bamboo cut in the hot-house of Dr. Pitcairn, at Islington, 

 was judged to contain tabasheer in one of its joints from a rattling 

 noise discoverable on shaking it, but being split by Sir Joseph Banks, 

 it was found to contain not ordinary tabasheer, but a solid pebble about 

 the size of half a pea, so hard as to cut glass." 



(II. By Sir Humphrey Davy. From the Journal of the Royal Institution.) 



On the 18th of November, a paper, by James Smithsbn, esq., F. E. S., 

 on the chemical analysis of some calamines, was read. 



Much uncertainty has hitherto prevailed on the subject of the compo- 

 sition of calamines. The author was induced to carry on his researches 

 by the hopes of obtaining a more certain knowledge of these ores, and 

 he considers his results as fully proving the necessity for new investi- 

 gations, and that the opinions which had been adopted concerning them 

 were far removed from the truth. Mr. Smithson's experiments were 

 made upon four different kinds of calamine : the calamine of Bleyberg, 

 that of Somersetshire, that of Derbyshire, and the electrical calamine. 



The calamine from Bleyberg was white, and had a stalactitical form ; 

 its specific gravity was 3.584. It became yellow under the blowpipe; 

 and when exposed to the heat of the interior blue flame was gradually 

 dissipated. It dissolved with eflervesceuce in sulphuric acid, muriatic 

 acid, and acetous acid. It lost by heat rather more than one-fourth of 

 its weight. It afibrded oxide of zinc, carbonic acid, and water, in the 

 proportion of 714, 135, and 151 ; there was besides found in it a minute 

 portion of tlie carbonates of lead and lime; but these the author con- 

 siders as accidentally mixed with the ore, and not in combination with 

 the other ingredients. 



The calamine from Somersetshire was of a mammillated form. Its color 

 was brown externally and greenish yellow internally ; its specific gravity 

 was 4.33G. It dissolved in sulphuric acid, with eftervescence : and when 

 analyzed by means of reagents, afibrded in 1,000 parts, 352 of carbonic 

 acid, and 648 of oxide of zinc. 



The Derbyshire calamine was in small crystals, of a pale yellow color; 

 their specific gravity was 4.333. When analyzed, by solution in sul- 



