ORGANIC CHEMISTRY. 



ORGANIC CHEMISTRY. 



There is no branch of chemistry more diffi- 

 cult, and yet more interesting, than that of or- 

 ganic chemistry; for in this the chemist finds, 

 added to his ordinary difficulties, and to his 

 many sources of uncertainty, the presence, and 

 very often the controlling influence, of a living 

 principle, which in some instances seems to 

 neutralize and overcome even the most power- 

 ful chemical affinities. " I would warn, there- 

 fore, the reader," to use the words of Dr. Thom- 

 son, "not to expect complete information in 

 this branch of science : the wonders of the 

 vegetable creation are still but very imper- 

 fectly explored ; many of the organs of plants 

 are too minute for our senses, and scarcely a 

 single process can be completely traced. The 

 multiplicity of operations continually going on 

 in vegetables at the same time, and the variety 

 of different and even opposite substances 

 formed out of the same ingredients, and almost 

 at the same time, astonish and confound us ; 

 the order, too, and the skill with which every 

 thing is conducted, are no less surprising; no 

 two operations clash ; there is no discord, no 

 irregularity, no disturbance; every object is 

 gained, and every thing is ready for its intend- 

 ed purpose. This is too wonderful to escape 

 our observation, and of too much importance 

 not to claim our attention. Many philosophers, 

 accordingly, distinguished equally by their 

 industry and sagacity, have dedicated a great 

 part of their lives to the study of vegetation. 

 But hitherto their success has not been equal 

 to their exertions. No person has been able to 

 detect the formative agent in plants, nor even 

 the principle which is always so busy in per- 

 forming such wonders, nor to discover him at 

 his work ; nor have philosophers been much 

 more fortunate in their attempts to ascertain 

 the instruments which he employs in his opera- 

 tions." A great variety of curious and inte- 

 resting facts, however, have been discovered. 

 These I shall attempt to collect and arrange, to 

 point out their dependence on each other, and 

 to deduce such consequences as obviously 

 result from the discoveries which have been 

 hitherto made. 



The farmer will, upon reflection, be able to 

 call to mind many circumstances, showing the 

 influence of the living principle upon the 

 chemical substances of organic matter. He 

 will remember, for instance, that the living sub- 

 stance flourishes in the very same position, 

 and under the very same circumstances, where, 

 when dead, it rapidly putrefies. Every plant 

 growing on the soil, or on a dunghill, testifies 

 to the fact. The living plants which flourish in 

 the same solution of a salt in which they are 

 dissolved, when dead, prove the same thing in 

 another way; and these proofs may be multi- 

 plied very easily on very slight reflection. And 

 as regards animal life, the very same results 

 are obtained ; the very gastric juice which the 

 living stomach holds for an age, dissolves that 

 stomach when dead. Animals can sustain a 

 temperature considerably greater than that 

 where the putrefaction of animal substances 

 rapidly proceeds ; and men even can exist for a 

 considerable period in an atmosphere heated 

 considerably above the boiling point of water. | 



In this sketch of organic chemistry, I shall 

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principally confine myself to the vegetable 

 branch of it, and briefly follow the progress of 

 a plant through its several stages of germina- 

 tion, its growth, and its decay, leaving the 

 reader to refer to other heads of this work for 

 the information he may need. 



Germination. That all plants arise from 

 seeds is now, I believe, undisputed by every 

 person, notwithstanding the very many puz- 

 zling phenomena which occasionally occur; 

 such as the profusion of some of the grasses, 

 occasioned by the application of certain ma- 

 nures. Thus, "by dressing certain soils 

 with bones and wood ashes, the white clover, 

 which contains this salt, appears in great quan- 

 tities. Now, phosphate of lime abounds in 

 bones and in the ashes of wood; other plants, 

 it is probable, require the same food. Thus, 

 after the great fire of London, says Mr. Play- 

 fair, large quantities of the Erysimum latifolium 

 were observed growing on the spots where a 

 fire had taken place. On a similar occasion, 

 the Blitwn capilatum was seen at Copenhagen, 

 the Senerio viscosus in Nassau, and the Spartium 

 scoparium in Languedoc. After the burnings 

 of forest pine in North America, poplars, ac- 

 cording to Franklin, grew on the same soil. 

 (Liebig's Org. Chem. p. 152.) 



Seeds, therefore, the farmer may rest as- 

 sured, are essential to the production of plants. 

 Now, the first movement of the seeds towards 

 the production of plants is denominated their 

 germination. To this certain requisites are 

 essentially necessary; such as moisture, mode- 

 rate heat, and oxygen gas. That all seeds re- 

 quire a certain degree of moisture before they 

 will vegetate, is known to every one : where 

 there is no moisture, there can be no germina- 

 tion. This, however, varies according to the 

 nature of the plant. Some of the mosses, for 

 instance, will germinate on walls and other 

 places where the supply is very limited; others, 

 such as the water plants, will only grow im- 

 mersed in water. The rice of Hindostan is 

 grown in swamps abounding with water, which 

 would be destructive to all the grain crops 

 of the English farmer. The water-meadow 

 grasses of our own country illustrate the same 

 position. The plant, too, has the power of de- 

 composing water, and assimilating its hydro- 

 gen in the formation of its own substances. 

 Water is composed of hydrogen and oxygen, 

 and these substances are always essential in- 

 gredients in vegetables. 



Heat is also necessary to germination : thus 

 few plants will vegetate below the freezing 

 point of water; nevertheless, this low tempera- 

 ture does not destroy their vitality, for every 

 farmer is aware that frozen seeds will vege- 

 tate after they have been thawed. As, how- 

 ever, there is a peculiar degree of moisture on 

 which every plant vegetates with the greatest 

 advantage, so there is a temperature pecu- 

 liarly favourable to the growth of every plant. 

 The ivy, the elder, and the honey-suckle, for 

 instance, invariably produce their leaves long 

 before any other English plant has felt the 

 warm reviving influence of spring. 



And, again, if the seed is not supplied with 

 oxygen gas, the most favourable supplies of 

 moisture and heat will not induce it to germi 



