182 NOTES ON HYDRAULIC LIME AND CEMENT. — MASoN. 



Unfortunately, where a quick-setting cement is demanded, 

 alumina is necessary, for all these straight silica lime cements 

 are slow setting under water, while they only attain their 

 greatest strength if kept under water, owing to the lime being- 

 converted into carbonate by atmospheric carbonic acid when 

 allowed to set in air. 



The writer has repeated some of Landrin's experiments, using 

 pure lime and native infusorial earth, after submitting the latter 

 to gentle ignition, and obtained excellent products. Further, 

 he finds that recently ignited infusorial earth slowly but surely 

 takes up lime from lime-water when kept in a solution of the 

 latter. The infusorial earth, which is perfectly friable after 

 gentle ignition, becomes quite hard after an emersion in lime 

 water for three months. The strength of the lime-water must be 

 kept up during the experiment. 1.222 grammes of such earth 

 in three months took up .549 grammes of lime. 



Limestone from Barra Head, N. S. 



The writer has for some time been experimenting with a 

 limestone from Barra Head, near St. Peter's, Richmond Co., N. S. 

 The first sample brought to him was composed of a single slab 

 of highly carboniferous limestone, which, when burnt, gave the 

 following analysis : — 



Lime 70.10 



Silica 16.30 



Alumina 6"50 



Peroxide of iron 1.36 



Oxide of manganese Traces 



Magnesia 1.13 



Soda and potash 61 



Sulphuric oxide 2.41 



This lime set and hardened rapidly under water. The 

 writer visited the property in the fall of 1902 and brought 

 away two large samples of the quarried stone. Unfortunately 

 other things intervened and only partial analyses were made 



