382 Clarice and Schneider — Experiments upon the 



since then it has acquired new significance, and it is empha- 

 sized by the new analyses. Leaving the waluewite for sepa- 

 rate consideration, it is to be noted that the three chlorites 

 studied by us are all typical members of Tschermak's ortho- 

 chlorite series ; which, according to him, are mixtures of two 

 end compounds, serpentine and ainesite. How amesite may 

 behave upon ignition, we do not know ; but serpentine splits 

 up, as is well known, into olivine and enstatite ; the latter 

 being insoluble in hydrochloric acid. Under Tschermak's 

 theory of the chlorites, a clinochlore of the composition SpAt, 

 should upon ignitiou yield about 18 per cent of enstatite ;■ or 

 in other words, the insoluble residue should contain at least 

 one third of all the silica in the mineral. Since no enstatite is 

 actually formed, or practically none, it is plain that the three 

 chlorites here considered contain no serpentine molecules ; 

 and hence, so far at least as these minerals are concerned, 

 Tschermak's theory falls to the ground. 



Approximately, but not exactly, the formation of spinel 

 from the waluewite and the chlorites, seems to follow a single 

 quantitative law. To illustrate this the empirical formulae 

 may be reproduced here. 



Waluewite, Al^CaJVTg^ (Si0 4 )„ 6 174 



Clinochlore, Al 3e Mg„H 141 (Si0 4 ) lt 111 



Leuchtenbergite, Al 42 Mg 86 H 143 (SiOJ 50 O 12I 



Ripidolite, Al 38 Mg 86 H 140 (SiO 4 ), O 113 



Upon ignition, of course, water is expelled, and the ignited 

 residue is empirically as follows : 



Waluewite, Al 86 Ca 24 Mg 62 (Si0 4 ) 28 149 



Clinochlore, Al 3g Mg 67 (SiOj 52 M 



Leuchtenbergite, Al 42 Mg 86 (Si0 4 ) 52 4g 

 Ripidolite, Al 38 Mg^SiO 4 ) 60 O 43 



Here we have in each mineral an excess of oxygen over 

 Si0 4 , and to that excess the amount of spinel residue is ap- 

 proximately proportional, thus : 



Found corrected. Calculated. 



Waluewite, 43-96 43-15 • 



Clinochlore, 16*63 14-80 



Leuchtenbergite, 18-05 ■ 1762 



Ripidolite, ' 18*49 15 -83 



Considering the impurities in the original materials, and the 

 unavoidable inaccuracies of manipulation, the agreement here 

 is as close as could be expected. The calculation assumes that 

 the excesses of oxygen represent quantitatively the amount of 

 spinel formed, and all the errors of analysis are accumulated in 



