Correspondence—A. R. Hunt. 525 
and even large Jurassic oysters, though in the last case they are apt 
to break again on ordinary handling. I have been too lazy to 
experiment with variations on the original recipe given me, but from 
conyersations with several chemists I gather that a simple solution of 
collodion in amyl acetate would probably act as well as the one I have 
been using. A. Mortry Davies. 
Unprerwoop, Wincumore Hitt, AMERSHAM. 
21st October, 1907. 
SALINE SOLUTIONS AND ORES. 
Srr,—The Guoroetcan Macaztne has afforded me the opportunity 
to champion many unpopular causes scouted elsewhere. Perhaps the 
greatest offender has been the significance of chlorides in granitic 
quartzes. The ubiquity of chlorides throughout the Dartmoor mass, 
and, so far as I am aware, in the Cornish elvans also, impressed me 
greatly. There must be some reason for it. I endeavoured to account 
for their origin, but could see no practical importance in what seemed 
to be a purely petrological puzzle. 
I now see that Mr. E. C. Sullivan, in discussing the interaction 
between minerals and water-solutions, points out that ‘ salt solutions, 
as decomposing agents, are much more active than pure water, and 
are comparable with acids in this respect.”? Mr, H. Foster Bain also 
points out, with reference to zine and lead, that ‘‘the ore bodies are 
doubtless due to concentration or re-concentration through the action of 
underground waters” (ature, vol. lxxvi, p. 559). Here we have 
a direct connection indicated between the Devon and Cornish mineral 
veins and the ubiquitous chlorides of potassium or sodium; also 
a possible explanation of the common connection between chlorides 
and the schorl rocks of the Western counties. 
If I can get metallurgists and chemists to perceive that chlorides in 
quartzes may have a distinct bearing on practical mining, and above 
all money-making, the investigation of the chloride problem will be 
secured, and there will be no need for me to further trouble my 
many geological friends by my importunity. 
When a most distinguished authority said that I based my world on 
an elephant, the elephant on a tortoise, and the tortoise on microscopic 
grains of chloride of sodium, he stated the absolute truth. The 
chlorides, both as to their origin and their significance, have puzzled 
me more than any other petrological conundrum. 
I am fully convinced that petrologists have no idea how ubiquitous 
the chlorides are in the Western granites. One amateur friend assures 
me they are very rare. An expert friend, to whose diagnosis I submit 
unreservedly, once sent me a slide for me to say whether there were 
any chlorides in it. The slide was mounted with an asphaltum ring, 
precluding the use of a high-powered objective, and the cover was 
not too thin. It abounded in chlorides—in fact, was rather a good 
example. It once took me about three evenings’ work with the > 
to conquer one refractory slide, but at last I detected one very minute 
cube. That of course sufficed to prove the presence of chlorides when 
the quartzes crystallised. Of course, my point is the diffusion of 
