220 E. W. Morley — Volumetric Composition of Water. 



can be assigned also to the Elba mineral. The ratios have 

 been calculated with A1 2 3 as unity because it shows less varia- 

 tion throughout the analyses than the other constituents. 



Ratios. 



Si0 2 : Al 2 3 (Fe. 2 0< 



Plattner's analysis as re-calculated by Brush 4*64 : 1* 



Plattner*s analysis newly re-calculated 4 - 64 : 1* 



Pisani's analysis 4*56 : 1* 



Pisani's analysis with assumed correction 4 56: 1* 



Rammelsberg's analysis on which he based his 



formula [5'01]: 1* 



Rammelsberg's later analysis 4-58: 1* 



Analysis of Hebron pollucite 4*53: 1* 



Proposed formula requires 4 - 50 : 1* 



Rammelsberg's formula requires 5 -00 : 1* 



Or. as he writes the latter 5*00: 1- 



R' 2 : H. 2 

 0-93 : 0-78 

 0-98 : 0-78 

 1-22 : 0-83 

 1-04 : 0-8a 



0-94: 0-90- 

 0-89 : 0-76 

 1-04: 0-52 



1-00 : 0-50 

 1-00 : 1-00 



200 



Leaving out of consideration Rammelsberg's first analysis, 

 there can be little doubt that the new formula expresses the 

 composition of Elba pollucite as far as the first three members 

 of the ratios are concerned, but the water is 0*8-0'9 per cent 

 higher in the analyses of that material than the formula re- 

 quires. A part of this excess may be accounted for by suppos- 

 ing it to take the place of any deficiency in the alkalies, as will 

 be noticed especially in the last analysis of Kammelsberg ; 

 hence, since the small excess of water cannot be introduced 

 into the formula without complicating it greatly and destroying 

 the metasilicate ratio, it is probably best to consider it as acci- 

 dental. The replacement of a small part of the alkalies by 

 water in the Elba mineral would explain its lower specific 

 gravity. 



It is satisfactory to notice that the historical first analysis by 

 Plattner confirms, in each of its re-calculated forms, the conclu- 

 sions arrived at in this paper. 



Sheffield Laboratory, Xew Haven, Conn. 

 January, 1891. 



Art. XXY. — The Volumetric Composition of Water ; by 

 Edward W. Morley. 



Until recently, our knowledge of the volumetric composi- 

 tion of water depended on the results of Humboldt and Gay- 

 Lussac. They presented their memoir to the Academy of 

 Sciences at Paris. The memoir was printed in full in the 

 Journal de Physique* and translated in Gilbert's Annalen der 



* Vol. lx, p. 129. 



