Allen and Clement — Role of Water in Tremolite. 117 



itself, that is, for the mineral to absorb water, was tested in 

 another way, viz., after the heating in moist air had been con- 

 tinued for 7 days, the loss then being- 29*5 mg , the process was 

 continued at 600° for one day. The gain was but *10 mg , or 

 practically nothing. On the following day the heating was 

 continued at 800°, when the loss was l'3 mg , and finally on the 

 next day the heating was again repeated at 600°. The gain 

 was only -2 mg . Evidently, therefore, it is impossible to get 

 equilibrium under such conditions as Friedel found he could 

 do with certain zeolites. 



The most obvious conclusion appears to be that the esti- 

 mated vapor pressure, which is of the same order of magnitude 

 with beryl as it is with kupfferite, is far too low and that it 

 would require a long time for the maximum vapor pressure to 

 develop, or perhaps the latter would finally reach a state of 

 " false equilibrium." * This raises the question, whether or 

 not the curves obtained for tremolite may not represent " false 

 equilibria," but the tedious nature of the work at atmospheric 

 pressure and the secondary importance of the question after 

 the relation of the water to the other components had been 

 established, decided us not to carry the matter further. 



Resorption of ivater by tremolite when heated with water 

 in a bomb to 00° . — Although no attempts were made to get 

 true equilibrium between tremolite and water vapor, some 

 eiforts were made to find whether water was taken up by the 

 dehydrated mineral under any conditions. The tremolite from 

 Ossining, N. Y., which had been heated to a constant weight 

 at 923°, where it lost 85*1 per cent of its water, was then 

 soaked in water for 20 hours, dried at 110° and blasted. It 

 was then found to contain 0'59 per cent of its weight, or 26*7 

 per cent of the original water content. It had therefore 

 absorbed 11 "8 per cent. A specimen of the Ham Island trem- 

 olite which had lost 47*7 per cent of its water at 933°, was 

 heated in a bomb, with water at 400°, for 6 days. It was then 

 dried at 110° and the water retained determined by blasting. 

 It contained 2*15 per cent, while originally it held 2*31 per cent 

 of water. There seems to be no difficulty, therefore, in revers- 

 ing the process when the active mass of the water becomes suffi- 

 ciently great. With beryl, however, the results were quite 

 different. A portion of this mineral which had lost 1*52 per 

 cent of its weight after a protracted heating at 800°, was 

 heated with 15 ce water at 420° for four days. Then the 

 beryl was removed and dried at 110°. On blasting 1*7568 gr. 

 lost -0203 gr. = ri5 per cent. The beryl originally contained 

 2*54 per cent water, so that the portion which was introduced 

 into the bomb must have had 2'54 — 1\52 = 1"02 per cent. 

 Hardly any water was therefore absorbed in the bomb. 



* Thermodynamics and Chemistry, Duhem. Translated by Burgess. Wiley 

 & Sons, 1903, p. 369. 



Am. Jour. Sci.— Fourth Series. Vol. XXVI, No. 152.— August, 1908. 

 9 



