COLZA.

315

Schrader endeavored to roast separately the different principles of coffee, bat none ofthem exhaled the aromatic odor of roasted coffee except the horny fibrous matter. Hetherefore concludes that this substance contributes mainly to the characteristic taste ofroasted coffee, which cannot be imitated by any other vegetable matter, and which, as wehave seen, should be ascribed chiefly to the altered cafeic acid. According to Garot, we®ay extract the cafeine without alteration from roasted coffee by precipitating its decoc-tion by subacetate of lead, treating the washed precipitate with sulphureted hydrogen,and evaporating the liquid product to dryness.

Of late years, much ingenuity has been expended in contriving various forms of appa-ratus for making infusions of coffee for the table. I have tried most of them, and find,after all, none so good as a cafeticre a la Belloy, the coffee biggin, with the perforated tin-Plate strainer, especially when the filtered liquor is kept simmering in a close vessel, setov er a lamp or steam pan. The useful and agreeable matter in coffee is very' soluble : itcomes off with the first waters of infusion, and needs no boiling.

To roast coffee rightly we should keep in view the proper objects of this process, whichare to develop its aroma, and destroy its toughness, so that it may be readily ground topowder. Too much heat destroys those principles which we should wish to preserve, andsubstitutes new ones which have nothing in common with the first, but add a disagreea-ble empyreumatic taste and smell. If, on the other hand, the rawness or greenness isn °t removed by an adequate heat, it masks the flavor of the bean, and injures the bev-® ra ge made with it. When well roasted in the sheet-iron cylinders set to revolve over abre, it should have a uniform chocolate color, a point readily hit by experienced roasters,Who now manage the business very well for the principal coffee-dealers both of London ? n “ Paris , so far as my judgment can determine. The development of the proper aroma8 a criterion by which coffee-roasters frequently regulate their operations. When it loses„ ore than 20 per cent, of its weight, coffee is sure to be injured. It should never he&r p , bd till immediately before infusion.

carbonized pitcoal. See Charcoal ; and Pitcoal at the end.j s ~OLCOTHAR OF VITRIOL (Rouge d'dngleterre, Fr.; Rothes Eisenoxyi, Germ.)h e f brown-red peroxyde of iron, produced by calcining sulphate of iron with a strongt e r ligating the resulting mass, and elutriating it into an impalpable powder. A bet-^ Way of making it so as to complete the separation of the acid, is to mix 100 parts ofthe green sulphate of iron with 42 of common salt, to calcine the mixture, wash away^suiting sulphate of soda, and levigate the residuum. The sulphuric acid in this

base

? x Pels the chlorine of the salt in the form of muriatic acid gas, and saturates its

_

from me - ^ ase Produced by the chemical reaction ; whence an oxyde will be obtained free*shinc? C '^’ muc h superior to what is commonly found in the shops. The best sort of pol-p re ° Powder, called jewellers’ red rouge or plate powder, is the precipitated oxyde of ironbininJn ^ adding solution of soda to solution of copperas, washing, drying, and cal-col 0r ® „ Powder in shallow vessels with a gentle heat, till it assumes a deep brown redC Q ® ee Iron.

aff tho ^^THANY, black rosin, the solid residuum of the distillation of turpentine, whenCOTrvr, has been worked off.

the Sev U NG MATTER. ( Matilre colorante, Fr.; Farbstoff, Germ.) See Dyeing ,frOLTTtu-r!' e ~ stu ® an ^ piguaents.

in Con n .HUM, a peculiar metal extracted from a rare mineral brought from Hadflam,found in e « tlCUt ‘ ^ * s a Lo balled Tantalium, from the mineral tantalitc and yttro-tanlalite,bessive etien - 11 bas hitherto no application to the arts. It combines with two sue-CoLZa 6 ^ ° f ox fg en > by the second it becomes an acid,an oil jn u n a var iety of cabbage, the brassicaoleracea, whose seeds afford, by pressure,PUrp oses c “ e ™ployed in France and Belgium for burning in lamps, and for many otheror clayey 1 , 8 I ,lant requires a rich but light soil; it does not succeed upon either sandy

be sown in T ?' ^be ground for it must be deeply ploughed and well dunged. It shouldto be plant i an ^ be afterward replanted in a richly-manured field. In October it is0r 10 inches asu* d* 15 or inehes apart. Colza may also be sowed in furrows 8

y e fresh'd 1 ^ ^ as .b ee n just cropped for wheat is that usually destined to colza; it may"Me befo re t?™ ac frantage. The harvest takes place in July, with the sickle, a"nctive of 0 ;j see< is are completely ripe, lest they should drop off. As the seed is pro-b°mpl e t e their 0 'T evel > only in proportion to its ripeness, the cut plants are allowed toa stack, anr i .v® 1 ," ra fr°n, by laying them in heaps under airy sheds, or placing them in

; Tha babbale " ‘ ng U With straw “

t ? l he air to dnf-t^ are tllras hed with flails, the seeds are winnowed, sifted, spread outae begi nn j no . * ’ V 1611 packed away in sacks, in order to be subjected to the oil-mill atthem 15 r* . Vlnte _ r * The oil-cake is a very agreeable food to cattle, and serves to

C0I2:

a i fflpoverisV„ eC lV 0ne ' 1 .J 0 defl ' a y the cost of tha mill.crish.es the soil verv much, a* rln. imlppH *1

very much, as do, indeed, all the plants cultivated for the