248 Contributions from the Sheffield Laboratory. 
being weighed as platin-chlorid of potassium, and the amount 
educted from the total chlorids. The water was determined by 
igniting the mineral with perfectly dry oxyd of lead, and the 
difference, between this loss and the total loss on igniting the 
mineral alone was considered to be fluorid of silicon. Analyses 
fe Mean. 
Hygroscopic moisture, ). : : “ 
expla 100°C t $0 3 6 Ls i 
- 13°89 13°87 13°89 eg teehee 6 ee 
Floor of silicon, = ES ees Sees eo ey ae 0-47 «0°47 
Sili $604. 4-062 8611-5... su. eee 
Alsmina with . Tittle t 45-11 $646 4656 gece ue 
Potash, oO ee aa as Sees 3 age ee? ie 
Lithia, - - Se aay lg e's 9°84 281 Kase oe 
99°49 
ah oxygen ratio of the R, i, Bi and H is 1:93: 20° 97: 18°51: 11°91, 
name Cookeite, after Professor Josiah P. Cooke, Jr., who I believe — 
was the first to discover its remarkable pyrognostic characters. 
2. Jefferisite, a new mineral species. 
In the Ninth ee to Dana’s Mineralogy, I described a 
chloritic mineral, which I referred with a query to vermiculite 
It is the well known brownish chlorite-like mineral from the 
esi quarry near Westchester, Penn., and like the 9 
eding mineral exfoliates in a ver shesaizaiss manner when 
heated. I have recently learned, through Professor Dana, that 
apa cart has determined vermiculite to be uniaxial in 18 
disti pecies. I propose for it the name Jefferisite, after the 
wall poe sarang m. W. _ Esq., of Westchester, the 
original discoverer of the mineral. 
have recently received from Mr. Raphael Pumpelly a similar 
mineral from Japan, possessing the same property of exfoliating 
when heated. Mr. Pumpelly informs me that it is found in the 
mountains of the Peninsula of sone southeast of Yedo, and 
Br in piyical Rush ETRE Pyrogn osc characters = Jefierisite. 
‘1 
oe Facters and 1 ee eee Bae TA nad (2) vol. a 
veel ; ae oe 
