OF ARTS AND SCIENCES. 457 



of the Lerni vermiculite, and Table II. shows the percentages of water 

 found in the same specimens dried at 100° C. 



16.72 16.72 



II. 



(2.) (3.) (Mean.) 



11.71 



(2.54) 

 j 9.13 I 



11.65 11.67 11.71 11.68 



Table III. gives the percentages of water found in air-dried specimens 

 of the Pelham vermiculite, and Table IV. gives the percentages of 

 water found in the same specimens dried at 100° C. 



III. 



(1.) (2.) (3.) (4.) 



Loss at 100° C. 10.83 10.72 10.80 



„ about 300° C. 4.35 > 



red heat 5.65) 



10.27 10.14 



20.83 20.99 20.94 



IV. 



(Mean.) 



11.21 11.50 11.13 11.43 11.32 



The marked hygroscopic character of the Culsagee, Lerni, and Pel- 

 bam vermiculites led to the idea that the discrepancies between the 

 published analyses of Jefferisite and Hallite might be due to the hygro- 

 scopic nature of these minerals. The water contained in each of 

 them was therefore carefully again determined. Table V. gives the 

 percentages of water found in air-dried specimens of Jefferisite ; anal- 

 yses (1), (2) and (4) of Table VI. give the percentages of water found 

 in the same specimens dried at 100° ; (3 a) gives the percentages of 



