WRITINGS OF JAMES SMITHSON. 5 



it after it is become transparent, is not owing to the fusion 

 of its surface by means of some of the ashes of the charcoal 

 settling upon it unobserved, appeared by its undergoing the 

 same change when fixed to the end of a glass tube, in the 

 method of M. DE SAUSSURE.* 



With acids. 



V. (A) A piece of Tabasheer, weighing 1.2 gr. was 

 first let satiate itself with distilled water ; its surface being 

 then wiped dry, it was put into a matrass with some pure 

 white marine acid, whose specific gravity was 1.13. No ef- 

 fervesence arose on its immersion into the acid; nor did 

 this menstruum, even by ebullition, seem to have any action 

 upon it, or itself receive any colour. The acid being evap- 

 orated left only some dark coloured spots on the glass. 

 These spots were dissolved by distilled water. No precipi- 

 tation was produced in this water by vitriolic acid, or by a 

 solution of crystals of soda. The bit of Tabasheer washed 

 with water, and made red hot, had not sustained any loss of 

 weight. 



The pores of the mass of Tabasheer were filled with 

 water before it was put into the acid, to expel the common 

 air contained in them, and which would have made it im- 

 possible to ascertain with accuracy whether any effervescence 

 was produced on its first contact with the menstruum. 



(B) Another portion of Tabasheer, weighing 10.2 gr. was 

 boiled in some of the same marine acid. Not the least pre- 

 cipitate was produced on saturating this acid with solution 

 of mild soda. This Tabasheer also, after having been boiled 

 in water, and dried by exposure for some days to the air, 

 was still of its former weight. 



VI. This substance seemed in like manner to resist the 

 action of pure white nitrous acid boiled upon it. 



VII. (A) A bit of Tabasheer weighing 0.6 gr. was di- 

 gested in some strong white vitriolic acid, which had been 



* Journal do Physique, Tom. XXVI, p. 409. 



