68 
THE CULTIVATOR. 
the yolk in a great number of samples, as well Spanish as French, 
and found them in all. 
The yolk being a true soap, soluble in water, it is easy to ac* 
count for the comparative ease with which the sheep that have the 
natural proportion of it are washed in a running stream. There is, 
however, a small quantity of fatty matter in the fleece, which is 
not in combination with the alkali, and which, remaining attached 
to the wool, keeps it a little glutinous notwithstading the most care¬ 
ful washing. 
This subject may be summed up in the comprehensive language 
of Mr. Luccock. “ He,” the northern sheep-master, after having 
applied his salving, “ finds this dirty coat as indispensably neces¬ 
sary to the good qualities of the fleece as it is to the health of the 
animal; without it, the wool becomes hairy, thin, and light; with 
it, the fleece is full, soft, and rich, possesses a sufficient quantity of 
healthy yellow yolk, and the qualities and condition of the wool are 
most wonderfully improved. From these circumstances we con¬ 
clude that the yolk is not only necessary to the production of a 
valuable fleece, but is the very pabulum of wool. The manner in 
which the yolk acts upon the wool is not accurately known. Some 
have considered it as the superabundance of that substance which 
forms the filament, and which, by some unknown process, while the 
pile is growing, is consolidated into a transparent mass; while 
others conclude, perhaps more reasonably, that it is a peculiar se¬ 
cretion which exudes through the skin, and, by intermingling with 
the pile, renders it soft, pliable, and healthy, affecting it much in 
the same way as oil does a thong ot leather when kept immersed in 
it and perfectly saturated. In general this substance has been no¬ 
ticed without any particular reference to the breed of the animal, 
or the qualities of the fleece which it bears; sometimes as perfectly 
disregarded as the sand and the hay-seed which are accidentally 
mingled with the pile. Yet the disposition to produce this valuable 
animal soap is certainly as important as some other characteristics 
of the sheep, and ought not to be overlooked when we describe 
their different varieties or select them for our farms.— Library of 
Useful Knowledge , Farmers' Series. 
_EXTRACTS._ 
CHEMISTRY FOR FARMERS. 
The excellent essay on lime, by M. Puvis, which we are in the course of pub¬ 
lishing in the Cultivator, has been re-published in a pamphlet form, with an 
introduction by Professor Renwick, of Columbia College, full of instruction 
to the farmer. The public, we understand, are principally indebted to James 
Wadsworth, Esq., for this publication. The introduction of Professor Ren¬ 
wick is explanatory of many of the principles of agricultural chemistry, and 
as it will be likely to aid the reader in understanding more distinctly the ob¬ 
ject and effect of liming lands, we suspend, for this number, the continua 
tion of M. Puvis’ essay, and insert the introduction entire. We heartily rej 
joice, that men of science are at last applying their labors to agriculture—the 
great business of our country, and of the civilized world; and in behalf of our 
brethren of the plough, we tender to the gentlemen who have interested 
themselves in the publication of this valuable pamphlet, our grateful acknow. 
ledgements.— Conductor. 
The chemical facts and principles which are applicable to agri¬ 
culture, are neither numerous nor complex. They are, however, 
t<> be found only in works on general chemis ry, in which they are 
intimately associated with laws and phenomena of a more abstruse 
description, and in connection with which they constitute a science 
of which the most learned are still students, and to attain which in 
its existing form may require years of close and attentive study.— 
The language, too, of chemistry, which, to those who study it in a 
regular course, serves as an artificial memory, and single words of 
which call up long trains of thought and experiment, presents to 
the uninitiated all the difficulties of a foreign tongue. 
Yet it cannot be doubted, that the practical farmer may derive 
important benefit from acquiring so much of this language as will 
enable him to understand the chemical explanation of the numerous 
changes which are continually taking place in the natural actions 
which it is his high privilege to call into his service, to direct in 
part, and modify in degree. So also are there certain chemical ele¬ 
ments and compounds, with the properties of which he ought to be 
acquainted if he wish to be able to direct his practical skill with 
more effect, even in circumstances familiar to him, but which may 
be absolutely necessary, or will at any rate save waste of labor and 
loss of time, when the knowledge acquired by practice in one place 
is to be employed in a new situation, and under a change of circum¬ 
stances. 
It is the object of this introduction to exhibit, in such form as 
may be intelligible to those who have not made general chemistry 
an object of study, a concise view of such of the laws and facts of 
that science, as are absolutely necessary for the agriculturist who 
may wish to improve his practice, and which are more particularly 
required by those who wish to avail themselves of the knowledge 
contained in the subjoined essay. To do this has been found no 
easy task. It would be in itself difficult, but to the author of this 
introduction has been more particularly so, as he has for years been 
in the habit of imparting instruction to those whose habits of life 
and thoughts are as remote as possible from those of the practical 
farmer; persons to whom the peculiar language of chemistry is an 
aid instead of an impediment; and who, with ample time at their 
command, have an opportunity of pursuing the study of the science 
step by step. Fully aware of these difficulties, both general and 
peculiar, this attempt would not have been made, and certainly not 
persisted in, had it not have been for the instances of an intelligent, 
scientific, and successful farmer, who has urged the completion of 
the task as an object likely to be beneficial to those, who, with per¬ 
haps equal zeal and native powers of mind, have not enjoyed, like 
himself, the advantages of a scientific education. 
The atmosphere which surrounds our earth is the first object to 
which our attention should be directed. This is the vehicle of the 
moisture, which, whether it fall in the form of rain or dew, run in 
streams or issue from springs, is absolutely essentia) to the success 
of the farmer's labor. It is also, as we shall presently see, impor¬ 
tant to him on other accounts. 
The greater part of the atmosphere is made up of a mixture of 
substances, each of which has the same mechanical properties as 
the whole mass. These air-like substances are known to chemists 
by the name of Gases. 
Of these gases, two make up by far the greater portion of atmos¬ 
pheric air, and exist in it in the proportion of about four to one.— 
That which is the largest in quantity and makes up nearly 4-5ths 
of the whole atmosphere, is called, in the Essay of M. Puvis, by 
the name of Azof, but is more usually known in English by the 
name of Nitrogen. 
This substance, although in the largest proportion, is the least 
important of the gases in its chemical effects. It does not aid in 
supporting ihe life of animals, nor in maintaining the burning (com¬ 
bustion) of inflammable bodies. 
The part of the atmosphere which is absolutely necessary for 
these purposes, is called by the name of oxygen , and nearly makes 
up the remaining fifth part of atmospheric air. In its support of 
life it always, and in maintaining combustion often, unites with a 
chemical element, which is called carbon. This is familiarly known 
as forming the principal part of charcoal. In its union with carbon, 
oxygen forms a peculiar gas known by the name of carbonic acid. 
Carbonic acid is always found in small quantities in the atmos¬ 
phere, to which it is furnished by the breath of animals and the 
fumes of burning bodies. It is, when in considerable quantities, fa¬ 
tal to the life of animals, but is prevented from accumulating to an 
injurious extent in consequence of its being taken up by water; it 
is therefore dissolved, in proportions about equal to those in which 
it is formed, by rivers, lakes, the ocean, and the moisture of the 
soil. 
Water exists in the atmosphere in the form of vapour. The great 
source of this vapour is the extended surface of the ocean; and it 
is governed by a mechanical law, by which it is continually tending 
to distribute itself uniformly over the whole surface of the earth. 
It may thus exist in as large quantities over the surface of the dry- 
est land as over that of the ocean itself. The tendency to equal 
distribution is continually counteracted by the changes in the sen¬ 
sible heat (temperature) of the atmosphere, and of the surface of 
the earth, which follow the alternations of day and night, and the 
vicissitudes of the seasons. By these alternations and changes, the 
vapour is caused to fall (precipitated) in the form of rain, snow, 
hail, dew, or white frost, according to circumstances. As such 
changes of temperature are more frequent on the land than on the 
