FERMENT.

461

®atting gets denser, the hand pressure should be increased in order to overcome the in-casing resistance to. the decussation.

j ^/' rst 'bin sheet of soft spongy felt being now formed, a second is condensed upon itTii 6 ™? nner > and then a third, till the requisite strength and thickness be obtained.

sse different pieces are successively brought together disposed in a way suitable to the„ a-for article, and united by continued dexterous pressure. The stuff must be nextJpBted to the fulling-mill. See Hat Manufacture.s ERMENT (Eng. and Fr.; Heft, Germ.) is the substance which, when added in acha quantit y to vegetable or animal fluids, tends to excite those intestine motions andVe® ' vb i c h accompany fermentation. It seems to be the result of an alteration which’pjj’ la ble albumen and gluten undergo with contact of air amidst a fermenting mass,ture R' ec 'P* tate or l°cs which fall down when fermentation is finished consist of a mix-Hqu °* fermenting principle with the insoluble matters contained in the fermentedtp .1 °f> s °me of which, like hordeine, existed in the worts, and others are probably genera-u T at the time.

t ale P r epare a pure ferment, or at least a compound rich in that principle, the precipi-yeast ^ a rated during the fermentation of a clear infusion of malt, commonly calledd ra i ® r harm, is made use of. This pasty matter must be washed in cold distilled water,a p u ] ari( t squeezed between the folds of blotting paper. By this treatment it becomesin ,l eru lent mass, composed of small transparent grains, yellowish gray when viewedSlui e COIn Pound microscope. It contains much water, and is therefore soft, like moisthronj 11 albumen. When dried, it becomes like these bodies, translucid, yellowishsoinb?’ ?°rny, hard, and brittle. In the soft humid state it is insipid, inodorous, in-ture of r 1 Water and alcohol. If, in this state, the ferment be left to itself at a tempera-n°fn e "° m 60° to 7(F F., but not in too dry a situation, it putrefies with the same phe-°1(1 uh a as Vegetable gluten and albumen, and leaves, like them, a residuum resembling

^neese.

portin^.heginning of this change, partictflarly if the ferment be enclosed in a limitedbo ft i c a °!i a ’ r> *here is an absorption of oxygen gas with a fivefold disengagement of car-by itself* ■ ® as ’ wb *' e acetic acid makes its appearance in the substance. When distilledand s 0 j 11 a ff° r ds the same products as gluten. Dilute acids dissolve it very readily ;Solv; lu , ,^ es P° l ash with the production of ammonia, a peculiar circumstance, for in dis-Th e s ^ U ' en the alkali causes no such evolution.

So bdion >r< f >ert ^ P° ssesse d hy yeast of determining the fermentation of a properly dilutedby com D i su = a r is very fleeting, and is lost by very trifling alterations. It is destroyedBlade jp T te desiccation, and cannot be restored by moistening it again. The attemptsa ad i 0 London t0 squeeze out the liquid part of yeast in bags placed in a powerful press,Martini tain a sob d cake, in order to transport ferment to India , have had but a veryhop ccass ’ hjr its virtue is so impaired that it will rarely excite a perfect fermenta-l ° 0ri| y pwi P re P arel l worts. The same method is adopted in Germany , to send yeastIf yeast h late ^stances> and therefore with more advantage.a nd b v i„ be boil ed for ten minutes, it loses the greater part of its fermenting power,,^hen ? er boiling it becomes inert.

* a ° u gh, on °? * s P° ure d upon yeast, it immediately destroys its fermenting faculties,Saa dth , p ar j i. enn S *1 off, it seems to carry no remarkable principle with it. One thou-a little strong sll 'P b uric acid equally deprives yeast of its peculiar property, and so does"dth thei r o° aCet ‘ c ac *d. AH the acids and the salts, especially those which part readily° r su Iphites X ^ en ’ P r °duce the same effect. A very small quantity of sulphurous acid,?blatil e 0 jj s 5 *“ sta rd powder, particularly the volatile oil of mustard, and in general the° rse -radish h con . ta * a sulphur, as well as the vegetables which yield them, such asto Pped bv a „ Sarlic, all kill the fermenting agent. Lastly, fermentation is completelya faring f erm ocler ate depression of temperature.

bother Wor ( . eiu ation the yeast undergoes a change; it loses the property of causingal ' v een r ° lerme at. This change probably depends upon the chemical reactionin» the |- e ment tbe su " ar that is decomposed; for a certain quantity of yeaste ^is quantii v rmen ^ at * on ob on 'y a certain quantity of sugar, and all The sugar exceed-jj ° 0s e experirn remai hs unaltered in the liquor. It has been concluded from some rath-a .^^laate to th” r’ taat on< ? P art a’ 11 ' a half °f yeast (supposed to be in the dry state)hau Ut '° n >s ferme e *i m ® ntat * oa of a solution of 100 parts of pure sugar. When suchWei S !, e< ^ f° r no ng, n ■ ? be precise proportion of yeast, the fermenting principle is ex-<bon' 1 0 '' the veasf V ^ e ^ st * s hjrmed in it. There is a deposite indeed to about half theSol >? by dry distillnt™^ 0 ^’ ?! a white matter insoluble in water, which affords no am-Qj} on j lon ’ an d * s incapable of acting as a ferment upon a fresh saccharine

gla^ a'humen posses, 8 “avertible into yeast during fermentation, vegetable gluten> animal fik..:,.,, , m °st rapid and energetic powers. But ordinary glue, ising-

ne , . - energetic powers. But ordinary glue, ising-

5 or caseum, albumiae, urine, and other azotized substances, all