as a Cement under Water. 101 



Trial was made of it by mixing with water to the consistence 

 of thin mortar, which was laid to the thickness of a 5- of an 

 inch upon bricks previously wetted, then dried in the air 

 and placed under water. 



On examination of cement prepared in this way from 1 

 parts of lime and 1 part of clay, after being six days under 

 water, the surface appeared coated with a film of vegetable 

 matter deposited from the water. 



In the large way, the drying and pulverizing of the clay- 

 can be dispensed with in the first instance, as it will only be 

 necessary to ascertain the loss in weight by drying (about 5-), 

 in order to arrive at the proper quantity to use in the state 

 in which it is when dug out, so that the bulk applied may 

 correspond to the weight required. The proportion of 

 weight to bulk of lime, after this has been burnt, 

 slaked, and sifted, may be also first ascertained, so as 

 to enable the operator to form his scale in both cases 

 by measure instead of weight. When the clay is brought 

 to the consistence of thick cream with water, it will form a 

 stifi" paste by the addition of the lime, which ought to be 

 thoroughly incorporated with it, in one or other of the 

 proportions above mentioned : the paste should be formed 

 into balls the size of a child's head, or thereabouts. It will 

 only be necessary to dry these balls in the sun previous to 

 calcining ; and the concluding process of pulverizing and 

 sifting can be done by any mechanical power most at com- 

 mand. The experiment should, however, be made on a 

 small scale at first ; that is, with merely a handful of lime, 

 in order to get at the proper quantity of clay to mix with it. 



H % 



