WRITINGS OF JAMES SMITHSON. 3 



duced by reflected and by transmitted light was very sensi- 

 ble. 



(B) Four bits of this substance, weighing together, while 

 dry and opaque, 4.1 gr., were put into distilled water, and 

 let become transparent ; being then taken out, and the un- 

 absorbed water hastily wiped from their surface, they were 

 again weighed, and were found to equal 8.2 gr. 



In the experiment I. (G), 75.7 gr. of this substance ab- 

 sorbed 69.5 gr. of distilled water. 



(C) Four bits of Tabasheer, weighing together 3.2 gr. 

 were boiled for 30' in half an ounce of distilled water in a 

 Florence flask, which had been previously rinced with some 

 of the same fluid. This water, when become cold, did not 

 shew any change on the admixture of vitriolic acid, of acid 

 of sugar, nor of solutions of nitre of silver, or of crystals 

 of soda; yet, on its evaporation, it left a white film on the 

 glass, which could not be got off by washing in cold water, 

 nor by hot marine acid ; but which was discharged by warm 

 caustic vegetable alkali, and by long ebullition in water. 



Upon these bits of Tabasheer, another half ounce of dis- 

 tilled water was poured, and again boiled for about half an 

 hour. This water also on evaporation left a white film on 

 the glass vessel similar to the above. The pieces of Taba- 

 sheer having been dried, by exposure to the air for some 

 days in a warm room, were found to have lost one-tenth of 

 a grain of their weight. 



To ascertain whether the whole of a piece of Tabasheer 

 could be dissolved by boiling in water, a little bit of this 

 substance, weighing three-tenths of a grain, was boiled in 

 36 ounces of soft water for near five hours consecutively; 

 but being afterwards dried and weighed, it was not dimin- 

 ished in quantity, nor was it deprived of its taste. 



With vegetable colours. 



III. Some Tabasheer, reduced to fine powder, was boiled 

 for a considerable time in infusions of turnsole, of logwood, 



