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before they can fully perceive the force of inuch of the reasoning, although they may readily apply to practice many of the facts therein stated.
One of the most fertile themes of discussion has been the substance called humus, or geine ; whether in its complex state, or resolved, perhaps converted, into humic acid, crenic acid, apocrenic acid, &c. Now Liebig's statements appear simply confined to these assertions ;
First ; that humus is not present in fertile soils in a soluble form, as these soils do not yield any thing to cold water, except traces of inorganic salts. Humus, even in the most trifling quantity, would color the water brown, whereas water in which these soils have been digested, is completely colorless ; moreover, the juices absorbed by roots from these soils are also free from color. Admitting even that the humus of the soil were converted into humate of lime, the existence of which therein bas, however, still to be proved, plants could only derive from this source a very small portion of the carbon they contain.
Secondly ; that on a given surface, either of woodland or meadow, from which large crops containing considerable carbon are annually removed without any replacement by manure, the soil becomes yearly richer in carbon under the form of humus or geine.' These facts being demonstrated, it is scarcely possible to believe, that plants derive their carbon by absorption directly from humus or humic acid, an acid which, by the way, has never yet been discovered in soils, and is obviously a product of the decomposition of humus by alkalies.
We cannot doubt, that the true function of humus, or rather mould, is to yield a constant supply of carbonic acid to plants, when we are taught, by the beautiful experiments of Davy, that they decompose this gas in large quantities.
So far is Liebig from denying the use of humus by his assertion that plants derive their great supply of carbonic acid from the atmosphere, that he merely asserts, that it does not act by direct absorption, but constitutes a source of carbonic acid, so constant, so gradual, so abundant, and, above all, so economical, that probably the utmost efforts of science will never discover one superior. Considered in this view, we cannot sufficiently admire the perfection of the provision, thus made by means so simple, for the abundant supply of the principal food of plants.
It is not worth while to notice the denial which has been made of the origin of nitrogen in plants from rain-water ; the fact of ammonia existing in this medium, and in snow, having been sufficiently proved by scientific inquiry, both bere and in Europe ; nor need we defend the very evident origin of a considerable portion of this ammonia from the decay and dissolution (styled eremacausis by our author) of animal organization. This latter fact, indeed, forms an essential link in the wonderful chain of decay and reproduction, which it was one of his principal objects to trace, and which is so well delineated in the foregoing extract from the lecture of Dumas.
It is admitted, that Liebig does not claim to be the discoverer of the existence of ammonia in rain-water.
This was known, even here, before his book appeared ; but he may justly claim the application of this and many other facts, which are now admitted without doubt into all considerations of vegetable physiology, such as the preservation of the purity of the atmosphere by the reproduction, by vegetables, of the oxygen consumed by animals, and the necessity of mineral or inorganic substances as food for plants. These, although to a degree known previously, have been placed by him in such new lights, and so many additional facts have been adduced, as have rendered them facts of sufficient certainty to guide the practical or experimental agriculturist. His statements concerning the amount of carbon annually removed from a given surface of ground in the shape of fuel
, cannot be controverted ; and where the forests are, as in Germany, under the most rigid control and scientific management, his authority cannot be doubted.
With respect to guano, the analyses made by the chemists, to whom he refers, Klaproth, Vauquelin, Wohlen, and Boussingault, were certainly not made with the article in its fresh state ; and although it is not impossible, that this powerful manure may contain a portion of humus, yet this humus is not absorbed directly by plants; and, were humus the chief cause of the powerful effect of this manure, there is yet more in inert peat mould.
Many of the most intelligent farmers in Germany have already testified to the value of the new views disseminated by Liebig, nor can it be much doubted, that, in proportion as they are spread here, they will be appreciated, and, as far as understood, applied practically.
The most valuable addition to this second edition is the extracts from the lectures of Dr. Daubeny on agriculture, in 1841, founded chiefly on this work of Liebig. In these, his principles, and their practical application, are fully discussed; besides which, they contain the results of many experiments, undertaken as tests for the purpose of proving these principles.
These lectures are but the commencement of a history of the experiments, which are, or will be, instituted in all countries under the auspices of science, for the purpose of the economical increase of the produce of the soil ; a purpose launched forth into the broad ocean of human intellect by the writings of the present age, with an impetus far exceeding all our conceptions of material mechanics ; and which, in its course, gathering strength upon strength, bids fair not only to connect all mankind into one community of praise to the great Author of all for the simplicity, the beauty, the abundance of his works and his care, but to banish from the earth the mass of starvation and misery with which the unavoidable distinctions of poverty and riches seem almost to have overwhelmed its most fertile portions.
ART. XI.-CRITICAL NOTICES.
1. – Sir Henry Cavendish's Debates of the House of Com
mons, from May, 1768, to June, 1774; commonly called “ The Unreported Parliament.”
It is known, that during an interesting period of British history, a period of six years from May, 1768, to June, 1774, no more than a very brief and meagre sketch of the debates in Parliament has been preserved. This blank was occasioned by a strict enforcement of the standing order for the exclusion of strangers from the gallery of the House. By a fortunate discovery, a series of manuscript reports of nearly all the principal debates during this period, taken down at the time by Sir Henry Cavendish, a member of Parliament has lately been brought to light. They are contained in forty-nine small quarto volumes. The discovery was made by Mr. J. Wright,
who undertook to arrange and prepare the whole for publication. The following is Sir Henry Cavendish's own account of his labors.
My original design was to take down the heads only of the several speeches; but finding, hy practice, even my inferior skill adequate to something rather more extensive, in the subsequent sessions of this Parliament the debates will be found more at large, except in the case of a few members, whose rapid delivery outran my ability to keep up with them. I am conscious of the many imperfections that will be found in them; some most certainly from inability ; some from my peculiar and inconvenient situation at the time of writing them; and some, I ain sorry to say, from the disorder that now and then used to prevail in the House, - where sometimes members, frorn an eagerness to hear others, or themselves, made so much noise as to drown the voice of the person speaking; sometimes premature applause for a former part of a sentence prevented the House from hearing the latter; and sometimes those favorite words, “Hear! hear!' so frequently echoed through the House, forbade all hearing. Many gaps, many broken sentences, will be found; but even many of the broken sentences, I believe, will not be altogether useless. Several speeches of the most able members are very imperfect; many sublime and beautiful passages are lost, I fear, for ever : the only comfort I have is, that I believe I have preserved more than the memory of any individual bas. I have not, in the smallest degree, certainly not wilfully, altered or misrepresented the sentiments of any one member.”
The great value of these papers will be more fully understood by the following extracts from the Editor's prospectus.
“ It may be gratifying to the subscribers to state, that the collection contains upwards of two hundred speeches of Mr. Burke which have never seen the light; together with a number of the most valuable speeches of Mr. George Grenville, Lorth North, Mr. Dunning, Mr. Thurlow, Mr. Wedderburn, Mr. Fox, Colonel Barré, Mr., afterwards Chief Justice, Blackstone, Alderman Beckford, Sergeant Glynn, Mr. Dowdeswell, Lord John Cavendish, Sir George Saville, &c. It embraces the whole of the stirring period of the publication of the Letters of Junius, and exhibits the feeling which prevailed in the House and in the country, previous to the unhappy contest which took place between Great Britain and her American Colonies. Among many others, it contains discussions on the following important subjects; Expulsion of Mr. Wilkes, Middlesex Election, Privilege of Parliament, Trials of Controverted Elections, Informations ex officio by the Attorney-General, Liberty of the Press, Power and Duties of Juries, Law of Libel, Rights of Electors, Salaries of Judges, Affairs of the East India Company, Proceedings against the Printers for publishing the Speeches of Members, Duration of Parliaments, Coin and Currency, Criminal Laws, Royal Marriage, Subscription to the Thirty-nine Articles, Civil List, Copyright, Corn Laws, Poor Laws, Administration of Justice in Massachusetts Bay, Boston Port Bill, Quebec Government Bill, &c. Of this period, Gibbon thus speaks in his Memoirs ; — The cause
of Government was ably vindicated by Lord North, a consummate master of debate, who could wield, with equal dexterity, the arms of reason and of ridicule. He was seated on the treasury bench, between his Attorney and Solicitor General, the two pillars of the law and State, magis pares quam similes ; and the minister might indulge in a short slumber, whilst he was upholden on either hand by the majestic sense of Thurlow, and the skilful eloquence of Wedderburn. "From the adverse side of the House, an ardent and powerful Opposition was supported by the lively declamation of Barré, the legal acuteness of Dunning, the profuse and philosophic fancy of Burke, and the argumentative vehemence of Fox. By such men, every operation of peace and war, every principle of justice or policy, every question of authority and freedom, was attacked and defended, and the subject of the momentous contest was the union or separation of Great Britain and America.'
“ A peculiar feature of these debates is, that they were all reported by one person, who was a member of the House, and therefore not liable to be turned out in the middle of a speech; and who had no inducement to undergo the immense labor, but the honorable desire of possessing a faithful record of the proceedings of the time. By the publication of this collection, the proceedings of a Parliament, which bas hitherto been called “THE UNREPORTED PARLIAMENT,' will, at the end of seventy years, be more fully recorded, by the talent and perseverance of one of its own members, than any portion of the Parliamentary History of this country, previously to the relaxation of the standing order of the House of Commons for the exclusion of stran
The work will be completed in sixteen parts, making four volumes in royal octavo, printed uniformly with The ParliaMENTARY HISTORY OF ENGLAND. It is but partial justice to say of the volume before us, the only one which has as yet been published, — that it more than answers the high expectation which the above notices are calculated to excite. Mr. Wright has executed his task with good judgment and skill. He has enriched the text with frequent notes, consisting of matter well selected and well applied, and throwing much light on the actors and events of the time. We cannot but regard this work as an important accession, as well to the history of the United States as to that of England. It has brought out for the first time, and in an ample form, many of the transactions of the British Parliament on American affairs in the early stages of the Revolution, and contains the opinions of the great British statesmen on the topics which were then agitating the minds of all parties in the two countries.