92
FERMENTATION.
acids, chlorine, iodine, bromine, empyreumatic oils, smoke, creosote, strong d eC ° C r eI .of codec, have the same salutary effect. All these agents are known to counteract lmentation, putrefaction, and that dry wasting of organic matter called eremacausis, ° r scombustion. It is most deserving of remark that the poisons chemically neutral or alk a11such as those of small-pox in man, and of typhus ruminantium in cows, lose their haful power when subjected to the action of the stomach ; whereas that of bad saus»=which is acid, resists the modifying power of the digestive organs. , eT e
Alcoholic fermentation has been copiously discussed in the Dictionary . I ma )'add that ammonia, being a product of that change in solution of pure sugar, P r0 Xf 8 . t jnpresence of azote in the yeast; and that sulphuretted hydrogen, being made ma f ]ea i,the disengaged gaseous products, by their blackening paper imbued with acetate ol * ^
proves the presence of sulphur. The acid liquor accompanying yeast may be "’a J)aSaway, without impairing materially its fermenting power, while the acid so removeof itself no such virtue. _ en .
Yeast, freed from all soluble matters by water, alcohol; and ether, contains, '“‘v'jio-dentlyof ashes—carbon, 50-6 ; hydrogen, 7-3 ; azote, 15; oxygen, sulphur, androus, 27-1, in 100 parts. Viewed atomically, yeast bears a close analogy to alb a r e-Like albuminous matter, yeast takes a violet tint with muriatic acid, and it may . a0 , eplaced as ferment by gluten. Caseum (the curd of milk) and flesh operate the ff j.effect. All these fermentative powers have the same globular appearance in 1 ;tcroscope with yeast. When the activity of yeast has been destroyed by lie at > jn a "can be restored by the positive energy of the voltaic battery, which causes its c0 . n0 pi-tion with oxygen. The best proportion of sugar and water, for exhibiting the P t0 Jena of fermentation, is 1 of the former to 3 or 4 of the latter, and 5 parts of s u ? a glj2a rof fresh yeast may be added ; though in the course of fermentation, 100 parts ol j 0 gdo not consume 2 parts of yeast, estimated in the dry state. The quickest f? rB> c f thetemperature is from 68° to 86°. A very little oil of turpentine or creosote, ormineral acids, prevents or stops fermentation completely ; oxalic and prussic aci p r0 nithe same effect, as also corrosive sublimate and verdigris. It has been ^ n0 " ( j ( jed t0time immemorial in Burgundy, that a little red precipitate of mercury, W . he \ a u twh e11the must-tun, stopped the fermentation. All alkalies counteract fermentation,. c0 pic
they are saturated it recommences. The first person who described the snicglobules of yeast with precision was Dcsmazieres, who arranged them amOo e jiotcodermes (fungus-skinned), under the name of mycoderma ccrevisite. They bla<$the flattened form of the globules of blood, but are rather egg-shaped. One-® ^ or 5point may be seen on their surface, which, after some days, is associated with > ’^ gS eothers. Their average diameter is from_1_to_l_of an inch. Someti® .
... , , „ 5000 4000 wh® 1 “
minute globules cluster round one of ordinary size, and whirl about with ibliquor in which the globules float is agitated. ..look' 11 ?’
Fresh yeast loses, by drying, 68 parts in the 100, and becomes solid, horn) ^terA*and semitransparent, breaking readily into gray or reddish fragments. " l its
resumes immediately its pristine appearance. When fresh yeast is triturn a ] Ill0 nds>own weight of white sugar, it forms a liquid possessing.the fluidity of oil 0 j n o-so® e 'and a ycilow color. The globules continue unchanged, except perhaps k ec0 tiffl®what smaller. Yeast in the dry state retains its fermentative virtue for a r| f rte d in®
Saccharins Fermentation is "that by which starch and dextrine are co ^gjnixsugar, as shown remarkably in the action of diastase upon these bodies. , en )perat a ^parts of starch paste with 1 part of dry gluten, and keep the mixture at a j a cti
of from 122° to 140° Fahr., we obtain a good deal of sugar and dextrine. ^ a
acid is also formed. Flour paste, long kept, spontaneously produces su =reaction. See Fermentation in the Dictionary .
Lactic Fermentation .—Almost all azotized organic matters, after bei ygenthe contact of air, become capable of giving rise to this fermentation. in*°jy
not come into play, except as the means of transforming the animal su ^ e bo ^
ferment. Diastase and caseum are well adapted to exhibit this c h aa = ^ in tters, V°that is to furnish the lactic acid may be any one of the neutral vegeta - tsl (o snS ’sessing a like composition with lactic acid, such as cane-sugar, grape gto p als° ,dextrine, and sugar of milk. All the agents which stop the ulcoho > For V T ° ; flactic fermentation ; while diastase and caseum are its two best exci to tb e
cing abundance of lactic acid, we have merely to moisten malt, to e*l ein ulsio n , e
for a few days, then to triturate it with a quantity of water, and ^ ' e -vj e then satl Jm,e,some days more in the air, at a temperature between 67° and 86 I • ,actate of 1 g;the liquor with chalk, after having filtered it, and thereby obtain i ^ , phospb®which may be crystallized in alcohol, to deprive it jof the dextrine ana ^ uS
and then decomposed by sulphuric acid. . ,, nhenoBi etll> '„]at S!
Lactic Acid , formed from curd (caseum), exhibits more remarkam I c oa,
whfn milk is left alone for some time it becomes sour, and coagu a