W On the solidifying, or induration of Chunam. [Apiufc 



it. They have further discovered that lime is more solu. 

 ble in a solution of sugar, than in water alone : the lime 

 decomposes the sugar, sets free the gaseous carbon and 

 oxygen which combine in the proportion to form carbonic 

 acid, and the lime having a very strong affinity for the 

 carbonic acid attaches it, and thus united with the indurating 

 principle, or with that gas which gives hardness to the lime-, 

 it becomes that hard and imperishable matter that it is found 

 in all buildings properly built, particularly in old Indian 

 masonry of brick and lime. If we examine a fresh brick it 

 will be found brittle and light — but examine a brick of old 

 masonry, it is as hard as granite. 



There is another purpose gained by this combination. 

 Bricks are made of clay, silex, and a certain portion of oxide 

 of iron, scattered by nature over and among matter, and 

 which gives the red colour to bricks ; these are porous and 

 capable of absorbing moisture — they consequently absorb 

 the jaggery water holding the lime in solution, this water in 

 the brick acts the same part that the unabsorbed jaggery 

 water does with the lime and sand, and forms within the 

 brick and in its pores a similar cement to that which binds 

 the bricks together, binding the minute particles of the 

 brick, and this accounts for the intense hardness of all the 

 old Indian masonry. 



In this country where the temperature is so high, evapora- 

 tion rapidly takes place. Moisture is necessary to assist the 

 lime in attracting and holding carbonic acid, therefore some 

 extraneous aid must be given which is afforded by the jag- 

 gery ; and further, masonry is so thick in general that the 

 carbonic acid that is always floating in the atmosphere would 

 be years, if it ever reached the interior work. In Europe 

 sugar is too dear to use, and on that account it has never 

 been used ; but hair is used in plastering to keep mortar 

 together. 



If a better rationale than the foregoing can be given, or if 

 there are errors in the conclusions drawn, it would be adding 

 to knowledge if it were afforded, and those errors pointed 

 out. 



