Correspondence. 193 
i<i Malison's hypothesis* of a continuous cloud envelope till after the 
Quaternary glaciation, consists in the extensive deposits of rock salt 
and gypsum round in strata as old as the Silurian and Cambrian, sihct 
these beds e-ould only be formed by evaporation of lagoons shut off from the. 
.sen, or of saline lakes, under <i drying atmosphere.'" (Italicised by the 
present writer. ) 
The physics and chemistry of this objection are defective. Even 
upon the assumption that the vast beds of gypsum, rock salt, or other 
minerals deposited from aqueous solution, were solely the result of evap- 
oration, it does not follow that such deposition was the result of an ab- 
solute, nor even partial, desiccation id' the basin Containing the solution. 
The deposition of soluble salts goes on from saturated solutions under 
any evaporation at all. ami if the water flowing into the basin had been 
already saturated at a higher temperature, the deposition of the salt 
would goon even with increasing depth of water in the basin, by the 
cooling effect of evaporation. 
It is at least possible that vast beds of gypsum were precipitated by 
the commingling of solutions of a more highly soluble salt of lime witli 
a solution of sulphuric acid or of an alkaline sulphate; in which case 
the precipitation of gypsum would go on independent of evaporation, 
and drainage entering the body of water from different areas might 
have supplied tlie solution necessary to continue the precipitation for 
some time. In the same way other salts could tie formed to such an ex- 
tent as to lie present iii greater quantities than would saturate the solu- 
lion. and hence they would be precipitated or crystallized out. 
Tlie precipitation of sulphate of lime would go on in the Pacific 
ocean to-day. provided there were discharged into its waters an,\ soluble 
salt of lime and an alkaline sulphate sufficient to charge its waters with 
more than about 1-400 of sulphate of lime. 
Many of the compounds of sulphur and chlorine with the non-metal- 
lic elements are volatile, and they may have been, and doubtless were. 
j. resen l iii the atmosphere during earlier ages to a greater extent I han at 
present. In that case, such compounds would be washed out of the 
atmosphere by rains, and coming in contact with solutions of t he alka- 
line earths and alkalies would form and precipitate or crystallize out 
I he more stable salts now in existence. The format ion id' sulphate of 
lime, common salt. etc.. would then proceed from abundant rains rather 
than from a period of dryness and excessive evaporal ion: t he less soluble 
salts would be precipitated as formed, and the more soluble ones would 
crystallize out from saturated solutions. It therefore does not follow 
that "these beds could only be formed bj evaporation of lagoons shut oil' 
from t he sea. or of saline lakes, under a drying atmosphere." 
Another argument, used more to show that the Ice age was caused i>\ 
the upheaval of temperate land areas than as an objection to the criti- 
*The writer disclaims any attempt t<> advance an hypothesis "i assumption ol am 
kind, but simply endeavors to make an interpretation el natural fai t- upon the basis ol 
known and admitted laws, lie docs not even assume that the cloud envelope w 
moved, but that its removal was geologically and physically recorded < 
Lit mates, pp. ty and 40. 
