1880.] NATURAL SCIENCES OF PHILADELPHIA. 323 



Weight. Total L.OS? from Incre- p. c. of p. c. of 



loss. 100^ C. ment total loss fr. 



ofloss. loss. 100°r 



V. Weight of iindried mica .S052 



" at 100° C. .7827 .0225 2.79 



" at 125° C. cooled 



for 8 minutes. .7757 .0295 .0070 .0070 3.66 0.89 



" at 150° cooled for 



3 minutes. .7682 .0370 .0145 .0075 4.59 1.85 



" at 170°-175° cool- 

 ed for 4 min. .7682.0370.0145 4.59 1.85 



" 190° cooled for 3 



minutes. .7647 .0405 .0180 .0035 5.03 2.30 



VI. "Weight of undried mica. .9855 



" at 100°C, heated 



several hours. .9615 .0240 2.43 



Below faint red heat. .9445 .0410 .0170 .0170 4.16 1.77 

 Heated to pale red at 



bottom of crucible. .9320 .0535 .0295 .0125 5.32 3.07 

 Heated to bright red at 



bottom of crucible. .9210 .0645 .0405 .0110 6.54 4.21 

 Heated to full red on 



whole crucible. .9148.0707 .0467 .0062 7.17 4.85 



VII. Total water. 



(a) Loss of weight at red heat, 7.30 per cent. 



(b) " " on ignition, 7.50 '• 



(c) " " " 3 times, 7.86 " 



From the above experiments of Mr. Haines in connection with 

 Nos. (1), (2) and (3) under "hygroscopic properties," we may 

 deduce the following percentages : 



For total water, we have (IV), 7.58 p. c. ; (VI), 7.17 ; (VII, a, 

 b, c), 7.3a, 7.50, 7.86. 



Mean total water, 7.48 per cent. 



For h3'groscopic water, driven off at 100°, we have 



Exp. (1) Exp. (1) Exp. (2) Exp. (3) 



Analysis I. Analysis II. Heated 1| hrs. Reheated 3 brs. 3 hrs. 3 hrs. 

 3.12 3.43 3.21 3.57 2.79 3.09 



Exp.IIaExp. lib Exp. lie Exp. II d Exp. III. Exp. IV. Exp. V. Exp. VI. 

 3 hrs. 5^ hrs, 5 hrs. 2 lirs. several hrs. 



3.14 3.33 3.42 3.69. 2.96 3.37 2.79 2.43 



