168 Dr. Thomas Thomson on [March. 



(8.) The process No. 7 is repeated thrice, and after each 

 soaking the cloth is exposed for some hours on the grass, 

 and finally dried in the stove. 



(9.) The cloth is steeped in a mixed ley of pearlash and 

 soda, of the specific gravity 1*01 to 1*0125, heated to the 

 temperature of 120°. It is allowed to drain for some hours 

 and then well washed. It is then dried in the stove. The 

 object of this process is to remove any superfluous oil which 

 might adhere to the cloth. Should any such oil be present, 

 the succeedingprocess, the galling, couldnot be accomplished. 



(10.) For the galling, 18 lbs. of alleppo galls are to be 

 boiled for four or five hours in 25 gallons of water, till the 

 bulk is reduced to about 20 gallons. This liquid, after 

 straining, is strong enough to impregnate 100 lbs. of cloth, 

 with the requisite quantity of nut galls. Of late years 

 sumach from Sicily has been substituted for nut galls ; 

 33 lbs. of sumach being reckoned equivalent to 18 lbs. of 

 nut galls. Sometimes a mixture of 9 lbs. of nut galls and 

 16 j lbs. of sumach is employed. 



In this liquor, heated to 80° or 100°, the cloth is fully 

 soaked. The sumach gives the cloth a yellow colour, which 

 serves to improve the madder-red, by rendering it more 

 lively. 



(11.) The next process is to fix the alumina on the cloth. 

 This step (as has already been observed) is essential, because, 

 without it the madder dye would not remain fixed. 



In this country alum is used by the manufacturers ; but 

 in many parts of the Continent acetate of alumina is em- 

 ployed. To form the alum liquor of the Turkey-red dyers, 

 to a solution of alum of the specific gravity 1*04, as much 

 pearlash, soda, or chalk is added, as is sufficient to preci- 

 pitate the alumina contained in the alum. Through this 

 muddy liquor, (which should have a temperature from 100° 

 to 120°,) the cloth is passed and steeped for twelve hours. 

 The alumina is imbibed by the cloth, and unites with its 

 fibres. 



(12.) The cloth thus united with alumina is stove-dried, 

 and then washed out of the alum liquor. 



(13.) These essential preliminary steps having been taken, 

 the cloth is ready to receive the red dye. 



From 1 to 3 lbs. of madder, reduced to the state of pow- 

 der, for every pound of cloth is employed ; the quantity 



