122 Observations on Licbig^s " Organic Chemistry" 



great is the effect, that in some fruits which do not possess much 

 juice, the process proceeds farther, and part is converted into 

 starch, forming a dry mealy fruit, which would have been sweeter 

 on a standard ; and fruits abounding in juice are thus the most 

 suitable for walls and warm climates. Fruit will continue to 

 deoxidate after pulling, most in the light, but if heat is present 

 will continue also ; and both heat and light should be kept from 

 ripe fruit; a cool dry air and little light will keep them best, 

 unless pulled before ripe. In some fruits, as plums, grapes, &c., 

 part of the skin is wholly deoxidated, and a waxy substance 

 abounding in hydrogen without oxygen is formed, called bloom, 

 which assists in preventing further action. In some, as in Cac- 

 tus Opuntia, a poisonous substance is formed. Heat seems thus 

 greatly to assist the action of light, though light acts as in that 

 of the harvest moons without heat ; the states of the moon are 

 said to have great effect on vegetation in tropical countries ; they 

 attract the atmosphere, also diminishing pressure, and assisting 

 expansion. The chemical rays in the beam of light should 

 have a powerful effect; and also electricity, which is present 

 often where not suspected. 



He next resumes the subject of the blossoming of trees ; and 

 attributes the cause of fruitfulness in vines to the pruning of 

 their branches. It is well known, however, to gardeners, that, 

 if the rods of young wood are left long and not pruned, there 

 is much more blossom ; in fact, the reason they give for pruning 

 is, that there would be more fruit than the plant could mature 

 if the rods were not cut short, and the more young wood they 

 want they cut the shorter. 



The special object of agriculture, he says next, is to obtain 

 an abnormal developement and production of the parts of plants 

 employed as food, or for purposes of industry. When we 

 want to give strength to the straw, the substances giving solidity 

 to the straw, as silicate of potash, must be given ; when we wish 

 to increase the quantity of seeds, nitrogen must be given. 

 Wild animals are devoid of fat, as compared with domestic 

 animals. Substances may be given, he says, to increase every 

 vital production; as charcoal powder will produce such an ex- 

 cessive growth of the liver of a goose as will cause its death. 

 The increase or diminution of the vital activity in plants, he 

 says, depends on heat and light, which we have not arbitrarily 

 at our disposal. 



The duty of the chemist is to explain the composition of 

 a fertile soil ; and on this head he enumerates the quantity 

 of alkalies contained in some of the most common of the 

 minerals ; as feldspar, albite, mica, and zeolite, which form 

 part of the most common of our rocks. He gives the state- 

 ment of the quantity of potash on an acre, if composed of these 



