On the Neutralization of Colour in mixtures of certain Salts, 485 
tion for a barrier of this kind led Sir Charles Lyell, however, to 
reject the idea of an original lake extension, and to refer the 
formation of our terraces entirely to the action of the sea during 
the slow uprise of the land at the commencement of the present 
epoch. In this he has been followed by all geologists who have 
subsequently examined these terraces. The difficulty may per- 
haps be surmounted by assuming the earlier and greater eleva- 
tion of that portion of the country lying to the east of the gneis- 
soid belt which connects our northern Laurentian district with 
the Adirondack Mountains of New York. The subsequent de- 
pression of this region would open an eastern outlet to the lake- 
waters, and gradually lower these to their present levels. But 
whatever the explanation, the undoubted fact remains, that, at 
the close of the Drift period, a vast freshwater sea extended over 
the greater portion of Western Canada, and at a level of at least 
500 feet above the present surface of Lake Ontario. 
Whilst the mollusca of this ancient lake were identical with 
existing species, its shores were peopled by the mastodon and 
mammoth, and probably by other extinct forms of life, together 
with various species that still survive. A great question remains 
to be solved. Our gravel beds may perhaps reply to this, and 
reveal to us that here, as in Europe, man and the departed mam- 
moth once trod the earth together. Could this be established, 
the discovery would be fraught with even deeper interest than 
that which attaches itself to exhumed human relics of the ancient 
plains of Picardy and the gravel-beds of Suffolk. Our Indian 
arrow-heads are disentombed by hundreds: the connecting link 
of the extinct tooth or bone may not be long forthcoming*. 
University College, Toronto, Canada. 
March 16, 1861. 
LXV. On the Neutralization of Colour in the mixtures of Solu- 
tions of certain Salts. By Freprrick Fizrp, F.R.S.E.F 
BELIEVE Maumené first pointed out the fact that when 
nitrate of cobalt is added to nitrate of nickel in certain pro- 
portions, the green and pink colours of the solution entirely dis- 
appear, and the liquid becomes colourless, or assumes merely a 
pale neutral tint. ver since the manufacture of the oxides of 
* Since writing the above, Albert Koch’s account of the discovery of the 
Missouri mastodon has come under the author’s notice. In this account, 
published in 1841, it is stated that the mastodon bones were found in more 
or less immediate association with large arrow-heads. The same writer 
also attests to the discovery of wrought implements in connexion with 
Edentate remains in Gasconade county, Missouri. 
+ Communicated by the Author. 
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