NOTES ON HYDRAULIC LIME AND CEMENT. MASON. 187 



" 111 the prepardtioii of these samples, the clay was dried and 

 ground with stone to such fineness as practically to leave no 

 residue Mhen sifted through a sieve of 10,000 iiiesli per square 

 inch. The raw inatei'ial thus obtained was mixed with water 

 and allowed to dry into cakes which were burned to a clinker, 

 coke being the fuel used in the burning. The clinker produced 

 was then ground to the same fineness and the cement resulting 

 gave the following analysis : — 



Silica. 22.80 per cent. 



Insoluble residue 1.10 " 



Ferric oxide | -. ,-, ,~.^. ,, 



Alumina j 



Lime (50.40 



Magnesia 1.04 



Sulphuric anhydride 1.30 " 



Carbonic anhydride and water 50 " 



Alkalies and loss . . .50 " 



100.00 



" An examination of this cement showed it to be a true Port- 

 land in every respect. It was burned to a s. g. of 8.175. 

 Briquettes were moulded, to be broken at 2, 4 and 7 days old, 

 and the following results were obtained. Unfortunately, I have 

 not obtained the results for the 28 days : 



2 days. 4 days. 7 days. 



450 lbs. per sq. inch 



470 



485 



" It will be seen from the breaking strains obtained, that the 

 cement is one which shows a stead}^ growth in tensile strength,* 

 which is one of tlie most important and desirable features of a 

 good Portland cement. The sample was also tested for sound- 

 ness, and neither under the boiling water test or under the Le 

 Chatelier test did it show the slightest sign of expansion or 



