Notices respecting New Books, 465 



Although the composition of this cement is not very different 

 from that of the Thorold cement, it is nevertheless of inferior 

 quality. 



Chasy Cement. — The Geological Commission of Canada has pre- 

 sented a magnesian limestone belonging to the Inferior Silurian, 

 which might serve to prepare a cement. This limestone, which ex- 

 tends over more than fifty miles, is argillaceous, compact, and homo- 

 geneous. Its colour is gray. Although containing magnesia, it 

 produces rather a lively effervescence with acids. Its composition is — 



« "to riJh . r Carbonate of lime 45-30 



BVii ao Carbonate of magnesia 12*77 



Argillaceous residue 19'77 



,«Jii9£,: Alumina and oxide of iron 12*52 



./TOi?' Water and loss 9*64 



Oneida Cement. — This is prepared from an earthy dolomite, which 

 is of a deep gray colour, effervesces slowly with hydrochloric acid, 

 and loses by calcination 37*5 per cent, water and carbonic acid. It 

 occurs in the Upper Silurian formation. Its composition is, — 



Carbonate of lime 39*91 



Carbonate of magnesia 34*15 



Silica and argillaceous residue .. 15*851qo.io 

 > Alumina and oxide of iron .... 6*25 j 



: Water 3*84 



, Magnesian Mortar. — The Geological Commission of Canada pre- 

 sented a specimen of a very remarkable rock formed of carbonate of 

 magnesia. It resembled a granular marble so closely that it might 

 have been mistaken for one, although it contains only insignificant 

 traces of carbonate of lime. It is besides ferriferous, and in certain 

 places is coloured green by oxide of chromium. It contains also 

 quartz, disseminated in white hyaline grains. The following ana- 

 lysis agrees with a previous examination by Mr. Hunt : — 



;^ Carbonate of magnesia 58*29 



Carbonate of iron 9*06 



Carbonate of lime traces 



Quartz 30*12 



Water and loss 2*55 



This carbonate of magnesia might be advantageously worked for 

 the preparation of the magnesian mortar, not alterable by the action 

 of sea- water, which has been recently proposed by M. J. B, Vicat. 



