122 Bricks rdudc of Anthracite and Clay. 



In a former number of this Journal, I detailed the effect of some 

 experiments which were made in Boston several years ago, on tlie 

 value of anthracite coal in the burning of brick, which were not suc- 

 cessful in consequence of the intense heat which was produced by 

 the use of an over quantity of it, vitrifying part of the contents of the 

 kiln ; the same effect would be produced even in the manner now 

 recommended, if too great a proportion of it was intermixed with the 

 brick earth. I have seen this take place and several of the bricks 

 altered in shape and converted into scoriae, a sort of semi-vitrifica- 

 tion taking place in the centre. As far as present experience affords 

 a criterion of judging, it will not require half the quantity of powder- 

 fed anthracite coal to produce the same effect as is generally allowed 

 of coal ashes in England ; less than half a ton of anthracite coal will 

 be sufficient for one hundred thousand bricks, while seven hundred 

 and fifty bushels of breeze and ashes are allowed In England for the 

 same nuifiber. The price of this sifted anthracite or refuse coal is 

 scarcely worth mentioning, as It is not calculated for domestic use, 



1-1 



and in Rhode Island, in particular, Is found an incumbrance by 

 the proprietors of the colliery. But it should be understood that the 

 principle upon which the value of each depends, is nearly the same; 

 the anthracite Is nearly a pure carbon, unmixed with any ashes, and 

 not being deprived of any part of its carbon by being partly con- 

 sumed In the grate, as is the case with respect to the cinders of bi- 

 tuminous coal, much less of the anthracite will therefore be required 

 to produce the intended effect; it should also be made much finer, 

 by passing it through a smaller skreen, otherwise in the process of 

 burning particles of it will remain unconsumed, rendering them liable 

 to crack and blister, as I have occasionally noticed. In the regula- 

 tion of the quantity of the anthracite coal, attention must also be paid 

 to the nature and qualities of tlie earth which is used for the manu- 

 facture of brick ; if it Is nearly a pure argil with a proper proportion 

 of silex only, vitrification In the kiln will not so easily take place, 

 and more of the coal dust may consequently be mixed with it ; but if 

 the earth contains a large proportion of calcareous matter it forms a 

 mixture of a very fusible nature, and consequently not so suitable for 



good 



The test of 



submitting a little of this earth to the action of marine acid may ea- 



be 



anthracite which it would be proper to mix with the clay in the com- 

 position of brick. 



