ON BLACK DYEING CLOTH AND HATS. 247 



retains an equal quantity of the like matter by reason of the defi- 

 ciency of heat in burning it. 



I tried parcels of well-burned chalk and stone-lime, some of 

 which were used fresh, others exposed two days, others six days, 

 others twenty-one days, in the same circumslances'; by making 

 several specimens of mortar with them, and e\pu,«in;^ I he s[(ecime!)s 

 in the manner already related ; and in a few moullis I was satisfied 

 that the specimens made with fresh lime were the liarde«;t and best, 

 and that the others were worse, as the lime of them had been long- 

 er exposed ; for those made with the lime which had been exposed 

 three weeks and had gained four or live ounces to each pound, 

 were so easily cut or broke, so much atfected by moislure and dry- 

 ing, and so liable to break off from the tiles, as to be utterly unfit 

 for the ordinary uses of mortar. 



After this there remained no doubt that lime grows worse for 

 mortar every day that it is kept in the usual manner in heaps or in 

 crazy casks ; that the workmen are mistaken in thinking that it is 

 sufficient to keep it dry ; that lime may be greatly debased without 

 slaking sensibly ; and that the superticial parts, of any parcel of 

 lime, which fall into small fragments, or powder, without being 

 wetted, and merely by exposuie to air, are quite unfit for mortar; 

 since this does not happen until they have imbibed a great deal of 

 carbonic acid gas. 



I now saw more clearly another cause of the imperfection of our 

 common cements. The lime being exposed a considerable time 

 before it is made into mortar, and drinking in carbonic acid gas all 

 the while, the quicker as it is the better burned, is incapaljle of 

 acting like good lime, when it is made into mortar ; and often ap- 

 proaches to the condition of whiting, which with sand and water 

 makes a friable perishable mass, however carefully it be dried. 



[Higgins^ Experiments and Observations. 



ON BLACK DYEING, 



AS APPLIED TO WOOLLKN CLOTH AND HATS. 



The dyeing of black has deteriorated so much within the last 

 forty years in England, and in this country as the copyist of Eng- 

 land, that the colors would be considered as unwearable, were not 

 the cloths as evanescent in their fabric as the colors are fugitive. 

 The faint miserable colors given to the blacks in the present day, 

 has been mainly the result of the prevailing passion for cheap 

 goods. To meet and indulge that ridiculous unprofitable passion, 

 the manufacturer lias been compelled gradually to make his goods 

 in the most flimsy manner, and the dyer to make his color at as 

 low a rate as possible. So much has the dyeing of black been 

 lowered in the west of England, that a piece of twenty yards of 

 broadcloth which forty years since was charged thirty shillings, is 

 now done for six shillings and eight pence, and the dyer makes 

 nearly the same profit now as he did then. 



Before the year 1790, all the black cloths dyed in England, ex- 



