604 



FARMERS' REGISTER. 



[No. H 



The following estimates of the composition of 

 some of the vegetable acids have been made by 

 Gay Lussac and Thenard: — 

 100 parts of oxalic acid contain: 



Carbon - - 26566 



Hydrogen - - 2-745 



Oxygen - - 70-689 



100 parts of tartaric acid contain: 



Carbon - - 24-050 



Hydrogen - - 6 629 



Oxygen - - 69-321 



Ditto citric acid: 



Carbon - - 33-811 



Hydrogen - - 6-330 



Oxygen - - 59-859 



100 parts of acetic acid: 



Carbon - - 50-224 



Hydrogen - - 5-629 



Oxygen - - 44-147 



Ditto mucous or saclactic acid: 



Carbon - - 33-69 



Hydrogen - - 3-62 



Oxygen - - 6269 



These estimations agree nearly with the follow- 

 ing definite proportions. In oxalic acid, 7 propor- 

 tions of carbon, 8 of hydrogen, and 15 oxygen; 

 in tartaric acid, 8 carbon, 28 hydrogen, 18 oxy- 

 gen-, in citric acid, 3 carbon, 6 hjdrogen, 4 oxy- 

 gen; in acetic acid, 18 carbon, 22 hydrogen, 12 

 oxygen; in mucous acid, 6 carbon, 7 hydrogen, 

 8 oxygen. 



The applications of the vegetable acids are 

 well known. The acetic and citric acids are ex- 

 tensively used. The agreeable taste and whole- 

 Bomeness of various vegetable substances used 

 as food, materially depend upon the vegetable 

 acid they contain. 



19. It is uncertain whether ammonia or the 

 volatile alkali exists ready formed in plants: but it 

 is evolved from many of them by the action of 

 lime or fixed alkali, assisted oy a gentle heat; 

 though it may be always imagined to be gene- 

 rated during the process by the combination of 

 azote and carbon. The ingenious researches of 

 M. Serturner, followed by those of other chemists, 

 have made us acquainted with the alkaline pro- 

 perties of several compound vegetable substances, 

 which were not suspected to belong to this class 

 of bodies, such as morphina, strychnina, brucina, 

 picrotoxina, delphina* ; these compounds, which 

 are found respectively in opium, nux vomica, 

 Bruceaanli-dysenterica, cocculus indicus, and Del- 

 phinium Staphisagria, agree with alkalies in their 

 effects upon vegetable colors, and in combining 

 with acids, into peculiar neutrosaline compounds. 

 They form the narcotic or poisonous principles of 

 the plants in which they are found, and probably 

 many more of them will be discovered. They are 

 not very interesting to the agriculturist, except 

 in this point of view, that possibly many noxious 

 vegetable substances may be rendered useful as the 

 food of cattle, by extracting their noxious princi- 

 ples by nseans of acids; and this is a subject well 

 worthy of experimental investigation. 



Fia:ed alkah may be obtained in aqueous solution 

 from moat plants by burning them, and treating 



• Many more have since been diacovered, as codeia, 

 narceia, aricina, &,c. All the compounds of this class 

 are composed of carbon, hydrogen, azote, and oxygen. 



the ashes with quick-lime and water. The vege- 

 table alkali, or polassa, is the common alkali in 

 the vegetable kingdom. This substance, in its pure 

 state, is white and semi-transparent, requiring a 

 strong heat for its fusion, and possessed of a highly 

 caustic taste. In the matter usually called pure 

 potassa by chemists, it exists, combined with water: 

 and in that commonly called pearl-ashes, or pot- 

 ashes in commerce, it is combined with a small 

 quantity of carbonic acid. Potassa in its uncom- 

 bined state, as has been mentioned, consists of 

 the highly inflammable metal potassium and oxy- 

 gen, one proportion of each. 



Soda, or the mineral alkali, is found in some 

 plants that grow near the sea; and is obtained 

 combined with water, or carbonic acid in the same 

 manner as potassa ; and consists, as has been 

 stated, of one proportion of sodium, and two 

 proportions of oxygen. In its properties it ia 

 very similar to potassa; but it may be easily dis- 

 tinguished from it by this character; it forms a 

 hard soap with oil : potassa forms a soft soap. 



Pearl ashes, and barilla and kelp, or the impure 

 soda obtained from the ashes of marine plants, are 

 very valuable in commerce, principally on account 

 of their uses in the manufacture oi'glass and soap. 

 Glass is made from fixed alkali, flint, and certain 

 metallic substances. 



To know whether a vegetable yields alkali, it 

 should be burnt, and the ashes washed with a 

 small quantity of water. If the water, alter being 

 for some time exposed to the air, reddens paper 

 tinged with turmeric, or renders vegetable blues 

 green, it contains alkali. 



To ascertain the relative quantities of pot-ashea 

 afforded by different plants, equal weights of them 

 should be burnt: the ashes washed in twice their 

 volume of water: the washings should be passed 

 through blotting paper, and evaporated to dryness. 

 The relative weights of the salt obtained will in- 

 dicate very nearly the relative quantities of alkali 

 they contain. 



The value of marine plants in producing soda 

 may be estimated in the same manner, with suffi- 

 cient correctness for all commercial purposes. 



Herbs, in general, furnish four or five times, and 

 shrubs two or three times, as much pot-ashes as 

 trees. The leaves produce more than the branch- 

 es, and the branches more than the trunk. Vege- 

 tables burnt in a green state produce more ashes 

 than in a dry state. 



The following table* contains a statement of 

 the quantity of pot-ashes afforded by some com- 

 mon trees and plants: — 

 10,000 parts of Oak - - 15 



Elm - - 39 



Beech - - 12 



Vine - - 55 



Poplar - - 7 



Thistle - - 53 



Fern - - 62 



Cow Thistle - 196 



Wormwood - 730 



Vetches - - 275 

 Beans - - 200 



Fumitory - - 760 



The earths found in plants are lour ; silica or the 

 earthof flints, alumina or pure clay, lime, andmag- 



* It is founded upon the experiments of Kirwan, 

 Vauquelin, and Pertuis. 



