of Chondrocyte, Humite and Clinohumite. 203 



The agreement of the above analyses with the theory is 

 very satisfactory. 



Previous analyses of Clinohumite. — The following analy- 

 ses are available for comparison, all made on mineral from 

 Mte. Somma. 

 I. Rammelsberg. Yellowish white crystals. Mean of three 

 analyses. 

 II. Rammelsberg. One of the above analyses showing the 

 highest Si0 2 and MgO. 



III. G. vom Rath. Orange yellow crystals. Mean of two 



analyses. 



IV. Wingard. Grayish to yellowish brown crystals. Mean of 



two analyses. 



I. II. III. IV. 



Si0 2 36-67 37-23 36-75 33-30 



MgO 56-83 57-78 54-88 51 '53 



FeO 1-67 1-57 5-48 9"7l 



.... Al a 3 -24 Fe 2 3 -89 



F 2-62 2-33 2-30 5*67 



HO .... .... .... 1'41 



eq. to F__ 



97-79 

 1-10 



98-91 



•98 



99-65 



•97 



102-51 



2-38 



Cal.H^O.- 



96-69 



1-64 



97-93 

 1-83 



98-68 

 1-81 



100-13 

 1-08 





98-33 



99-76 



100-49 



101*16 



In the first three analyses the calculated water represents the 

 quantity necessary to yield the ratio RO : (F+OH) = 9 : 2, 

 and as in previous instances it makes the analyses add up much 

 nearer 100 per cent than before. The ratios are as follows : 



Si0 2 : RO 



I. -611 : 1-444 = 3-80 : 9 



II. -621 : 1-466 = 3'81 : 9 



III. -613 : 1-448 = 3'81 : 9 



These approximate to 4 : 9 and thus substantiate in a satis- 

 factory manner our formula for clinohumite. 



The results of Wingard, analysis IV, differ from those of 

 other investigators. No proof is given that the material which 

 he analyzed is clinohumite except that it was obtained from 

 Prof. Scacchi, and there has undoubtedly been some mistake 

 for his analysis yields a ratio of SiO a :RO = 1'95 : 5, which is 

 very close to 2 : 5 as required by our formula for chondrodite. 

 The fluorine and water are low, as in his other chondrodite 

 analyses and the calculated water that we have added is that 

 required to complete the ratio SiO a : RO : (F+OH) = 2:5:2. 



