﻿Skey.^ — 071 the Alkalinity or Acidity of certain Salts and Minerals. 329 



Next to lithia is magnesia, then lime, soda, and aftervxirds potash. In 

 this connection it is proper to remark that lithia is the only base which 

 readily attacks platinum when fused upon it — a pretty good test of strength 

 one would think, and proving, as far as a single result has weight, that the 

 relative position I here assign to this base is correct. 



Both potash and soda, however, have certainly an appearance of being far 

 more powerfully alkaline than any of the bases just compared with them, 

 but this is due simply to the fact that they dissolve in water to a larger extent 

 and with far greater speed than these bases, whereby they are enabled to act 

 with greater facility, and effect more, in a given time. 



The fact is that in our use of the term alkalinity hitherto we have not 

 expressed absolute potentiality, but rather energy or speed of action, and this 

 speed being dependent (other circumstances being equal) upon the degree of 

 solubility in water of the substance tested, we have thus unconsciously per- 

 verted the true meaning of the term (alkalinity), by making it denote a 

 certain degree of solubility — a quality which we do not know is the least 

 related to it. 



It only remains to notice that in relation to rocks the terms basicity and 

 acidity have, by the facts above stated, their significance enlarged and their 

 appropriateness rendered still more apparent than before, while the term 

 neutrality is now shown to be predicable of certain of them and to be equally 

 significant. 



The character of rock masses, or portions of them, in these respects may be 

 disco vei'ed in a very direct and simple manner, by just pounding a portion of 

 them upon litmus paper moistened and properly prepared, when, according to 

 the results and manner of sampling, we know oflT-hand the true condition of the 

 specimen as a whole, or of any partic^^lar portion of it ; and, knowing this, we 

 leai-n at once the genei-al afiinities of such rocks or portions of rocks, or to 

 particularise whether they are absorbent of acid silicates or silica, or of basic 

 silicates (as the earthy or alkaline ones), or whether, as in the case of clay or 

 clay slate, they are negative to both these classes of bodies. 



I may add, in conclusion, that the rationale of the new process for the 

 retention of the fertilizing constituents of sewage by means of phosphate of 

 alumina is readily explicable by the fact that this is an acid salt (see table) ; 

 it is thus enabled, to chemically absorb all the more basic organic portions 

 of such sewage, these being generally the most valuable for manure, as they 

 are, I believe, the most noxious to animal life. 



