Want of Identity between Microlite and Pyrochlore. 119 



with oxalate of ammonia, a precipitate which was converted into 

 sulphate of lime, equivalent to 0.08 lime. Thus, 



Titanic acid, ..... 80. 



Oxide of tin, "^ 



^^^"' I . . . . 11.8 



cerium, [ 



uranium, J 



Lime, 08.2 



100.0 



"This mineral is therefore identical with that analyzed by Woh- 

 LER. The absence of protoxide of manganese and water, and the 

 smaller proportion of oxide of iron in this specimen, as indicated 

 by the blowpipe experiments, will account for the larger propor- 

 tion of titanic acid given in the analysis." p. 34. 



Then follows a quotation of the analysis of Pyrochlore by Woh- 

 LER, with which Mr. Hayes identifies his own results upon the 

 Microlite. But when we find, on comparing the two analyses, a 

 difference of more than 17 per cent, in the acid, and of one third 

 in the principal base, as well as a wide discrepancy in volatile 

 matter, and call to mind that these results are deduced from a 

 single trial, and that upon one grain's weight of the mineral, we 

 must believe, that the conclusion of Mr. Hayes cannot be sus- 

 tained upon such slender grounds ; and inasmuch as Mr. Tes- 

 CHEMACHER rcfcrs to the analysis for the confirmation of his views, 

 is it not possible that Mr. H. in turn, has unconsciously been in- 

 debted to the mineralogical evidence for a portion of his confi- 

 dence? 



In order to speak from present knowledge on the subject, al- 

 though I have no reason to doubt the correctness of former results, 

 I subjected 2.142 grains of the above mentioned crystal to the 

 following examination; premising however, that my inquiry was 

 chiefly directed to the proofs of columbic acid in the mineral, and 

 not to a rigid determination of proportions in the different con- 

 stituents. 



A. The powdered mineral was white, with only a faint tinge of 

 yellow. Heated for half an hour to redness, it scarcely changed 

 in color ; and lost 0.060 in weight, which equals 2.801 per cent. 

 It was then intimately mixed with six times its v/eight of bi- 

 sulphate of potash, and the mixture maintained in fusion for half 

 an hour. Successive portions of water were boiled upon the 



