CAR
CAR
( 267 )
feeds are ripe, the crop is cut down and dried;the feeds are rubbed out, and the reft of theplant is burnt in very Ample furnaces, the tem-perature of which is juft high enough to caufethe afhes to enter into a ftate of femifufion, andconcrete into compact cellular malfes. Themofl efteemed variety of this fait is called fwectbarilla ; it is of a greyifh blue colour, and iscovered over with a faline efflorefcence whenexpofed for a time to the air: it is exceedinglyhard, and when applied to the tongue difcoversa {harp pungent alkaline flavour.
We poffefs an interefting analyfis of the fal-fola foda by Vauquelin : f a remarkable quantityof azot enters into the compofition of this vege-table, thus giving it a ftriking analogy to animalmatter. 500 parts of the recent plant whencarefully burnt afford oil and ammonia, andpruflic acid, and leave behind roo parts ofafhes. 500 grains of the afhes when carefullylixiviated afford 1x3 grs. of muriated foda, andr 59 grs. °f cryftallized (68 grs. of dry) carbonatof foda, the infoluble refidue confifts of 204 grs.carbonated magnefia, and roo grs. of fand andoxyd of iron; to which are to be added 23 grs. ofwater not as a neceffary but an accidental part,and therefore fubjeft to conftderable variation.
The Alicant barilla being compofed of thefame falfola foda, contaminated in fome degreewith weeds and other impurities that are un-avoidable where a large quantity of materialsis operated on, ought to bear a confiderable re-semblance in its analyfis to that of falfola fodajuft mentioned. Mr. Kir wan g has examinedthe component parts of fweet barilla, but unfor-tunately we are not able to trace the fmalleftfimilarity between the refults of his analyfis andthat of Vauquelin: according to him a poundtroy of barilla contains
P 42I2i9< 250
1*27
125
70
960
Dry cauftic foda
ditto impure
ditto mixed with muriated foda
Sulphat of foda
Muriat of foda
Carbonic acid
542.8 6 Lime
127
1 3*-23
249-58
2o
861.32
4306.49
J453-5I
5760.00
Magnefia
Alumine
Silex
Unexamined earthCharcoal
Water
A minute examination however into the ex-periments upon which the aboye proportions artsfounded will difcover fome inconfiftencieS whichforbid us to place an implicit reliance on them-Thefe we fhall mention, not with a view to de-preciate the well earned reputation of Mr. K.but to fliow the neceflity of a further examina-tion into a fubject fo intimately conne£ted withfome of our mofl important manufactures. Itappears from Mr. K’s experiments that of thewhole 5760 grs. of barilla, 2857 were foluble inwater, the infoluble refidue when reduced to thefame apparent drynefs as the original barilla,amounting to 2903 grs. or fomewhat more thanone half. Now 480 grs. (or one ounce) of theentire barilla when treated with muriatic acidloft 80 grs. of carbonic acid, therefore the wholequantity of carbonic acid in a pound of barilla— 80 X 12 = 960 grs. But 480 grs. of theinfoluble refidue yielded by the fame treatment125.5 g rs - carbonic acid, and as the wholequantity of this amounted to fomething morethan 6 ounces, the total amount of carbonicacid in the refidue is = 125.5x6= 753 grs-Hence 960 grs. — 753 = 207 grs. indicate thequantity of carbonic acid contained in the folublepart of the barilla. But 207 grs. of carbonic acid'indicate only 491.6 of dry, or 1293 grs. of cryf-tallized, carbonat of foda, and it is not probablethat the foda contained in the barilla was verycauftic, fince Mr. K. obtained cryftals from thelixivium without, as appears, taking any mea-fures for faturating the alkali further than per-forming the evaporations and coolings, to thenumber of 18 in the open air. Another objec-tion arifes from the amount of carbonic acid inthe infoluble refidue. The only ingredients inthe refidue capable of uniting with carbonicacid are the lime and magnefia,but 543 grs. lime require 444.2 carbonic acidand 127 grs. magnefia 95.9
540.x
The whole amount however of carbonic acidcontained in the refidue is = 753 grs. there-fore (753 — 540.1 z~) 212,9 grs. of carbonicacid remain, without any bafe with which theycan combine.
It is alfo obvious that the amount of charcoalis exceffively exaggerated. The infoluble refi-due containing the charcoal, was, after a longlixiviation with hot water, dried in a heat belowrednefs, and was then fuppofed to have loft allits water, it was then calcined at a white heat,
C Examination of Alkalies arid in bleaching.
2 L 2e