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Sr/Ip/iuru: Addon Vegetable Matters. 389 



tTiat thi: affinity of the fulphuric acid for water dimiiiifhes in proportion to the fquare of th« 

 quantity of water it contains. 



Though we have reduced the general a£lion of the concentrated fulphuric acid upon ve- 

 getable matters to the formation of water, of acetous acid, and the feparation of carbone, 

 we muft here remark, that in fome cafes the a£lion becomes more complicated ; that fome- 

 times, alfo, vegetable acids are formed ; that the formation of a fmall quantity of alcohol, 

 even in fubfiances not faccharine, fuch as gum, unfized paper, &c. likewife occafionally 

 accompanies the foregoing phenomena ; and, laftly, that there is In many circumflances- 

 a difengagement of carbonated hydrogene gas more or lefs abundant. But thefe multiplied 

 products do not take place fo frequently as the compofition of water, of vinegar, and the 

 precipitation of carbone, the conftancy of which is invariable during the a£lion of concen- 

 trated fulphuric acid upon vegetable matters. They are In fome meafure phenomena ne- 

 ceiTary to the former. They depend upon the different proportion of the principles which 

 compofe vegetable fubftances. They take place more efpecially in thofe which contain a 

 greater quantity of hydrogene. The delcription of thefe, and the conliderations to which 

 they may lead chemifts, belong to the general and complete hiflory of vegetable analyfis 

 which we propofe to publilh- when our work (hall be finilhed. Laftly, thefe productions 

 of alcohol, of various acids at the fame time, and of carbonated hydrogenous gas, indicate a 

 more profound alteration in the vegetable matters treated by the fulphuric acid ; a compli- 

 cation of eff'e£ls, which, though it originates in the change of equilibrium occafioned by the 

 powerful attraction of this acid for water, cannot be well developed until after the explana- 

 tion of the new procefTes of analyfis, the methods and refults of which we (hall hereafter 

 prefent to the chemical world. 



Befides this multiplication of efi'e£ts and complicated combinations which are fome- 

 times obferved in vegetable matters treated with the concentrated fulphuric acid, an- 

 other alteration fometimes takes place in this laft. "When the fubftances placed in 

 contact with it contain too fmall a proportion of o.xygene to form the water required for it» 

 faturation, their hydrogene then unites with a portion of the oxygene of the acid itfclf, and 

 the fulphureous acid is formed. This cfte£t Is more particularly remarked in oily fubftances. 

 It takes place only till the quantity of water necelTary for the faturation of the acid Is af- 

 forded, and ceafes as foon as this faturation is effetled. 



This a<Slion of the concentrated fulphuric acid Is Itill more complicated on animal than 

 on vegetable matters, becaufe the animal matters themfelves are more compounded. Though 

 the affinity of the acid for water be the caufe, the formation of this liquid Is not only ac- 

 companied with that of a vegetable acid and t!ie precipitation of carbone, but ammoniac is 

 likewife formed. No efcape of any volatile principle is perceived. The azote, which forms 

 part of thefe fubftances, unites with a portion of hydrogene, and conftitutes the volatile alkali, 

 which combines with the fulphuric acid, or witli tlie acid which is at the fame time com- 

 pofed, while another part of the hydrogene forms with the oxygene of the fame fubftances 

 that water which is rcquifite to faturatc the fulphuric .acid. But in thefe cafes, as in the 

 experiments with vegetable fubftances, the quantity of carbone, which exceeds that required 

 to compofe the new acid, together with a portion of hydrogene and oxygene, will be fet at li- 

 berty, and falls down In the form of magma, of flock -., or 01 black powder. In this manner It 

 it that in the cafe of burns, frequently fo dangerous, which are produced by the concentrated 



fulphurie 



