•2^8 j9>is of Tanning and of Dyeing compared. 



obfen-ations and experiments. We flmll not in this place enter into the detail of tlic changes 

 and improvements he has made in the diflerent branches of the tanning art; but we mull add, 

 that the procelles have been repeated in all the laboratories of the Polytechnic School, by 

 the greateft number of {he pupils ; that the operations on different kinds of Ikins were 

 all concluded In eight, ten, twelve, or fourteen days at mod ; that the leather thus manu- 

 faf^urcd was completely faturated with tan, and of a quality fupcvior to the leather prepared 

 h)' the old method which is to be-mct with in the market ; ami laftly, that to thefc advantages 

 •the method of Seguin unites iimplicity, facility, and certainty of fucccfs. A difcovery of 

 this importance, in an art fo necelTary to our wants, entitles the author to the eftcem and 

 'gratitude of the public ; and thcfc fcntimcnts are more efpecialiy due to the citizen who 

 facrifices his individual intcreft to the general profpcrity, and is defirous of communicating 

 the fruits of his rcfearches. The advantage of public utility conftitutcs his rccompenfe, 

 and enables him to difrcgard the clamours which envy, ignorance, and the prejudice of 

 old habits never >fai! to raife againft every ufeful innovation. 



After the two fittings employed by Citizen Seguin to explain the nature and properties of 

 tan, the order adopted in the couri'e of vegetable chemiftry was rcfunied in the fchool. The 

 alkalis, the ligneous part, and the colouring matter were fucceffively examined ; the laft of 

 which naturally led to an explanation of tht* principles of the art of dyeing, the different 

 proceffes for fixing colours, and afcertaining their qualities. In treating of thefe different 

 objeftsj fome confiderations were prefented refpefling the new properties which fluffs ac- 

 <]uire by tinflorial proceffes. 



The procefs of dyeing ought not to afford fimply a colour to pleafe the eye, but fliould 

 effeft a kind of colouring tannage capable of adding to the properties of the web, and to 

 render it lefs foluble or putrcfcent. This object is generally negle£led or little known, but 

 it cannot be indilTerent. It is not only of importance with regard to economy, but we do 

 not hefitate to fay, equally fo for the prefervation of health. This may eafily be conceived 

 if attention be paid to the circumllances, that cloths of the fame kind and fabric differ con- 

 fiderably according to the dye ; that fomc are dry, brittle, of little durability, not adapted to 

 preferve or retain caloric; others are foft, fpongy, capable of retaining damps and exhala- 

 tions of every kind; and by the fuccefTive aiflion of light, air, and caloric, may either un- 

 dergo a fort of oxidation that deflroys their texture, or elfe pafs to a kind of putrefadlion, 

 which forms a continual atmofphere round the body, and more or lefs affeds the health. 

 It is in the midfl of armies under tents, in camps, where a great number of men are ex- 

 pofed to the fame kinds of fatigue and intemperance, and difler only in the colour of their 

 dotliing, that we may afcertain the truth of thefe obfervations. It is in the magazines of 

 the military hofpitals, where the clothing of men is depofited, that a very marked difference 

 in the fmcU and porofity of the fluffs is obferved, according to the colour with which they 

 are charged. 



After a fuccefCve examination of the different produdls of vegetables, the attention of the 

 fchool was direfted to the alterations they undergo after death, by the a£lion of light, 

 caloric, air and water. Thefe fubjc£ls led to the theory of the vinous and acetous fer- 

 mentations, and the production of alcohol and ether; and laflly, the courfe was terminated 

 by an examination of the phenomena of putrcfadion, which reftorcs to the atmofphere and 

 to the earth thofc pruiciples which the aftioa of vitality had before extracted. 



During 



