222 On the Clinochlore.of Chester Co., Pa. 
water and filtered. The solution was super-saturated with nitric 
id and precipitated lukewarm by chlorid of barium. The sul- 
phate of baryta was filtered, washed with boiling water, dried 
and incinerated, weighing 1:800 grammes, equivalent to 24°84 
per cent. of sulphur. 
16. Deducting the difference of oxyd of nickel in the two ex- 
periments ($ 8, 9 and 12) from the amount of oxyd of iron ($ 10) 
the analysis will stand thus: ; 
In 100 parts. 
TNH ci Sige ice ee ‘ . ~ AL34 
Nickel, . . i‘ j ‘ : 4:55 
opper, 1:30 
Lead, oc 0:27 
Baloborn =... ‘ " : ; 24:84 
Silica and insol. silicates, ¥ : ~ 25°46 
_ Alumina, ‘ : eee: 1:70 
99:46 
17. After deducting the sulphur necessary for the conversion of 
the lead (0-04) and the nickel (2-47) into sulphurets, and the sul- 
phur (1°32) and iron (1-15) necessary to form with the copper, 
copper pyrites, there remains 21-01 sulphur, for 40-19 iron. The 
latter would require for its conversion into monosulphuret, 23°25 
sulphur. A small portion of the iron may however be due to the 
gangue. 
Arr. XX.—On the * Clinochlore”? of Chester Co., Pa.; by Mr. 
W. J. Craw, First Assistant in the Yale Analytical Laboratory. 
Tue optical and blowpipe characters of this mineral were de- 
scribed by Mr. Wm. P. Blake in the American Journal of Science, 
2nd Series, vol. xii, p. 339; also vol. xiii, p. 116. - 
The remarkable results which he obtained by examination 
with polarized light have led to my undertaking a complete 
gave as the constituents, Si, 41, #e, @:, Mg, and H with a trace of Ca. 
