On ilie Sleeping (if JVooL 43 



ot5erating, as formerly, with a scries of colours taken as it 

 were at random, it is necessary to find precisely the shade., 

 required, to. follow the insenaible gradation from light to 

 dark through an harmonious successijn of thirty or forty 

 colours. But how can a dyer, however he may be accus- 

 tomed to all the operations of this kind, be sure of obtain 

 ing invariable results, when, besides a multitude of well 

 known causes, minute diiierenccs in the degree of twisting 

 alter the affinity of the light, and when the least mixture 

 in the substances to be dyed causes a coi-.siderable variation 

 in the affinity for the colouring principle? Previous Cx\pc- 

 rimeiits made on th.e wool of animals in different states, 

 caused M. Hoard to imagine that a more extensive investi- 

 gation of the subject would make him acquainted with the 

 cause of the changes he had before observed. 



M. Tessier, to^whom agriculture owes such important 

 improvements, facilitated his researches by procuring him 

 fleeces of Merinos in tlie grease from animals in health, dis- 

 eased, and such as had died of the rot. 



The wools of the healthy, dead, and diseased animals, 

 corresponding to the numbers 1, 2, 3, were employed sepa- 

 rately, together, and mixed v, it h scrapings {pelare), wool 

 of very inferior quality, and which has besides been altered 

 by lime. 



Scouring and bleaching are so intin}ately connected 

 with the operations of dyeiiig, that the author thought fit 

 to begin his comparative observations with these prelimi- 

 nary processes, and even to extend them to the grease, the 

 constituent principles of which were precisely explained in 

 INI. Vauquelin's memoir on the nature of tliat substance. 



The ao-ents which he employed for scouring wool, either 

 in the fleece or spun, are : 1. Grease ; 2. Soap ; 3. Caustic 

 potash ; 4. Hot water ; 5. Boiling water; Q. Flanders soap. 

 J. These wools being treated separatelv, according to the 

 universal custom, were not completely freed from grease. 

 No. 1. was very white, perfectly free from all impurityj 

 without the smell of sheep ; but, on rubbing it between the 

 fin<rers, a matter somewhat greasy might be perceived. The 

 wool of the beast No. 2, which hi:d died of the rot, was 

 extremely dirty, charged with earth and animal matters: 

 after being scoured it had still a yellowish gray colour, some 

 smell, and was more greasy than the preceding. In the 

 fleece of No. 3, attacked with a languid disease, were a 

 great quantity of ticks. That insect had not a little con- 

 liilKitcd to aggravate the disease oi the animal, whose spft, 



weak 



