24 WRITINGS OF JAMES SMITHSON. 



They were not scratched by a pin ; a knife marked them. 



b. One of these crystals, exposed to the flame of the blow- 

 pipe, decrepitated and became opaque, and shone with a 

 green light, but seemed totally infusible. 



Borax and microcosmic salt dissolved these crystals, with- 

 out any effervescence, producing clear colourless glasses. 

 Carbonate of soda had little if any action on them. 



c. According to Mr. Pelletier's experiments* on the 

 calamine of Fribourg in Brisgaw, which is undoubtedly of 

 this species, its composition is, 



Quartz - - - 0.60 



Calx of zinc - - - 0.38 



Water - - - 0.12 



1.00. 



The experiments on the Ilegbania crystals have had 

 different results ; but, though made on much smaller quan- 

 tities, they will perhaps not be found, on repetition, less in 

 conformity with nature. 



23.45 grs. heated red hot in a covered crucible, decrepi- 

 tated a little, and became opaque, and lost 1.05 gr. but did 

 not fall to powder or grow friable. It was found that this 

 matter was not in the least deprived of its electrical quality 

 by being ignited ; and hence, while hot, the fragments of 

 these decrepitated crystals clung together, and to the cruci- 

 ble. 



d. 22.2 grs. of these decrepitated crystals, = 23.24 grs. of 

 the original crystals, in a state of impalpable powder, being 

 digested over a spirit-lamp with diluted vitriolic acid, showed 

 no effervescence ; and after some time, the mixture became 

 a jelly. Exhaled to dryness, and ignited slightly, to expel 

 the superfluous vitriolic acid, the mass weighed 37.5 grs. 



On extraction of the saline part by distilled water, a fine 

 powder remained, which, after ignition, weighed 5.8 grs. 

 and was quartz. 



* Journal de Physique, Tome XX. p 424. 



