106 Allen and Clement — Role of Water in Tremolite. 



was allowed for complete dehydration. The losses are there- 

 fore too small, but since the general form of the curve is 

 similar to that of the others, and the form of the curve is the 

 most important point, the curve is given for the sake of com- 

 pleteness. The curve for the tremolite from Ham Island, 

 Alaska, the purest of all the specimens, was determined 

 with the greatest degree of completeness. On account of the 

 tedious nature of the work,* fewer points were determined on 

 the other curves, and in none of them was the dehydration 

 carried to the end, but only so far as to show beyond doubt 

 that all the curves were of the same general form. An excep- 

 tion should be made of the specimen from Eussell, N. Y. 

 (IY-IY, fig. 3), which contains less water and more iron than 

 any of the rest. There is an interruption in the continuity of 

 the curve between 835° and 865° where no water appeared to 

 be given off. A partial explanation may be found in the fact 

 that oxygen appears to be absorbed here ; at any rate the 

 powder, at first slightly greenish, becomes brown on continued 

 heating. This absorption might partly offset the loss of the 

 water. The data from which all the curves are plotted are 

 found in Tables % 3 and 4. 



Table II. 



-Loss of Water by Heat. Tremolite (Ham Island, Alaska). 

 t 2 grams powdered mineral taken. 





Time 



Temper- 

 ature 



Weight 



Loss 





Time 



Tem- 

 per- 

 ature 



Weight 



Loss 



1 



9 



hrs. 

 5f « 

 5 " 



500° 

 500° 



26-6865 

 26-6798 

 26-6798 



•00 



•0067 



•0067 



1 



o 

 3 

 4 



2| hrs. 



3 



5 " 



\\ « 



890° 

 890° 

 894° 

 890° 



26-6753 

 26-6751 

 26-6744 



26-6743 



•0112 

 •0114 

 •0121 



1 



5 " 1 750° 



26*6781 -0084 

 26-6780 -0085 



•0122 



2 



°2 



750° 



1 



2 

 3 



2 " 



6 



7 " 



920° 

 918° 

 918° 



26-6739 

 26-6722 

 26 6721 



•0126 



I 

 2 



5 



4+ " 



801° 



805° 



•26-6781 

 26-6778 



. -0084 



•0087 



•0143 

 •0144 





1 



2 

 3 

 4 

 5 

 6 



6 



6 



Q. « 



6 

 5 

 3 " 



933° 

 933° 

 933° 

 930° 

 933° 

 930° 



26-6701 

 26-6680 

 26-6667 

 26-6658 

 26-6646 

 26-6644 





1|5 " 845-850° 

 2|6 " 845° 



26-6774 

 26-6776 



•0091 



•0089 



•0164 



•0185 

 •0198 

 •0207 

 •0219 

 •0221 



1 

 2 

 3 

 4 



4 " 

 6 " 



5 " 



5 •< 



6 " 



863° 

 863° 

 863° 

 860° 

 862° 



26-6772 



26-6769 

 26-6764 

 266761 

 26-6763 



•0093 

 •0096 

 •0101 

 •0104 

 •0102 



5 





1 



2 



4^ " 877° 

 2-J " | 875° 



26-6758! -0107 

 26'6756| -0109 





*If any fluorine escaped during the dehydration of the other tremolites. it 

 must have been very little, for the microscope did not detect any lack of homo- 

 geneity, while, when the Gouverneur tremolite was heated 240 consecutive 

 hours at about 950°, the loss was - 5 per cent in excess of the water and the 

 mineral showed a very evident change. 



