152 
s i 
Dr. NATHANIEL Haycrorr has reprinted his} inaugural ad- 
dress, delivered before the Leicester Literary and Philosophical 
Society, on the Limits of Scientific Inqiiry; and we find also 
the abstract of a paper read at the last meetiag of the Natural 
Science Section of the Sheffield Philosophical Society by the 
President, Dr. Hime, on Phenomena and Forces, both rather 
extensive subjects for an hour’s discourse. 
THE following is from the Fournal of the Society of Telegraph 
Engineers :—“ Thanks to the noble exertions of the illustrious 
president of the Italian Geographical Society, the idea of an 
Arctic expedition under the Italian flag is gradually working 
its way into their minds. Funds have been offered, and the 
prospect is brightening that the old voyage of the Zev/, though 
the’ first, will not be the last of the Italian Arctic expeditions.” 
The same journal says that Signor Guido Cora announces his 
intention of editing an Italian geographical periodical, to be 
entitled A‘smos, the first number of which is to appear on 
January 1, 1873. 
Tue following is from the School Board Chronicle :—‘* New 
York has 101,883 scholars to rather over a million of inhabi- 
tants ; these children receive their instruction from 2,765 mas- 
ters (i.c., on2 teacher to every thirty-six pupils) ; the educa tional 
budget amounts to very nearly 700,000/., or 72. for*each child. 
In England, in one year, 35,999 men and 49,522 women were 
found uaable to sign the marriage register.” 
Numerous seals, very rare in these waters, are making their 
appearance at the mouth of Holy Loch andin Loch Long, in the 
Frith of Clyde. 
WE learn from the American Agriculturalis: that it has been 
finally decided to locate the arboretum, for which a large bequest 
was made to the Harvard University by Mr. Arnold, of New 
Bedford, on a farm, about ten miles south of Boston, where the 
School of Agriculture already exists. The details of the work 
are to be under the immediate control of Prof. Sargent, who is 
eminently well qualified for it. He proposes to lay out the 
ground (137 acres of well-diversified land) as a natural park, 
with drives and walks tastefully arranged, and leading from one 
family to another, in scientific order, of all the trees and shrubs 
hardy in that climate. 
A ‘*CENTENNIAL Commission” has been appointed by the 
American Congress to mature a scheme for the celebration of 
the nation’s hundredth anniversary in 1876, by holding an 
International Exposition in Philadelphia, which shall be ‘‘the 
graadest the world has ever seen.” The sum required to con- 
duct it properly is estimated at $10,000,000, and each State is 
called upon to subscribe its share of the amount as definitely 
fixed by the Commission. At a recent public meeting in Phila- 
delphia $100,000 worth of stock was taken in fifteen minutes. 
Tue American Palestine Exploration Society, of which we 
have already made mention in our columas, is about sending off 
an expedition for the purpose of carrying out the objects of that 
body. Acc ding to the /wdependent, it is to be under the direc- 
tion of Lieut. E. Steever, U.S.A., who will have special charge 
of the topographical survey, and of the preparation of a reliable 
map. He will be accompanied by Prof. John A. Payne, late of 
Robert Coliege, Constantinople, who will superintend the 
archeological department, and make what collections he can in 
natural history aad geology; but, being himself especially a 
botanist, he will devote his priacipal attention to that branch. 
Mr. Van Dyke and other gentlemen will probably accompany 
the party to the field, and among them will be an artist of con- 
siderable reputation. This labour is one, of course, that will 
require some time for its completion ; and, according to the 
Independent, atleast six years will be necessary to accomplish 
its object thoroughly, even allowing for the assistance of a British 
society (organised for a similar purpose) in doing its share of the 
work, 
NATURE 
THE DIOSMOTIC PROPERTIES OF COLLOIDS* 
i 
UTROCHET, in his researches on osmose, examined the 
properties of certain organic non-crystallisable substances — 
(later named colloids by Graham). mas 
Comparing the colloids gelatin gum-arabic, and albimen 
(from hens’ eggs) with cane sugar, he thus expressed numerically — 
the endosmotic power of these substances :—Gelatin, 3 ; gum- 
arabic, 5°17; sugar, 11; albumen, 12, Thus the endosmotic 
force attributed to the colloids was cunsiderable, in the case of 
albumen exceeding that of sugar. ; 
These results must, however, be considered in great measuce 
fallacious, as,|while the specific gravities of the solutions vee 
(101) their degrees of concentration were very differeat. Th 
solutions of gelatin and albumen contained 4'1 per cent. of these — 
substances, while the sugar solution scarcely contained 2°5 per 
cent. of sugar. On this ground the sugar must be ranked above — 
the colloids. ‘ 
There is another circumstance to be considered. Dutrochet — 
used the colloids in their natural state (common gum-arabic and _ 
albumen direct from the egg), and in this form they contain over 
3 per cent. of mineral substances, chiefly salts of lime and potash. 
Since Graham pointed out the great difference between crystal- 
loids and colloids, as regards diffusion in water and passage — 
through a membrane, it was to be expected that the presence of — 
crystalloids in the colloidal substance would considerably mask the — 
diosmotic properties ofthe latter. In the writer’s experiments he 
employed colloids freed from mineral substances, comparing their — 
diosmotic properties with those of the same substances in the 
natural state. Contrary to the generally received opinion that — 
these substances havea high endosmotic power, he found that this 
is not the case, though certain variations are met with, which ’ 
will presently be explained. y 
Solutions of pure colloids showed, when of moderate concen- — 
tration, a very weak endosmose. The properti-s of the mem- 
brane, however, distinctly affect the resulis. Animal bladder, — 
parchment, and artificial cellulose, are very near one another in 
this respect. With the first two the concentration of aa albumen 
or arabin solution might be ra’sed to about 10 per cent. without 
any perceptible increase of volume in the solution, at the expense 
of the pure water. Tannin gave a slight endosmose; a 10 per 
cent. solution in 24 hours received ro cc. water (the membrane ~ 
being parchment). The degree of concentration now given may — 
be considered about the limit within which, for these substances, Em, 
and with the membranes named, no addition of water Le 
place. With the artificial cellulose, the limit seems to be some- — 
what lower, for a 9 per cent. arabin solution gave (with it) a per- — 
ceptible, though very weak endosmose (about 045 cc) in 24 _ 
hours, and a tannin solution 7 per cent. increased in yolum 
o’S cc. in the same time. 4 ce 
On comparing with colloids in the impure state, it was found — 
that while a 10 per cent. arabin solution received hardly any 
water through the parchment, (about 0°5 cc.), an equally concen- _ 
trated solution of common gum-arabic increased in volume, in 
the same circumstances, about 2°55 cc. Kk 
When a pyroxilin membrane was used with the pure colloids, 
the endosmotic action was considerably greater than that which — 
took place in the other membranes. Thus with pyroxilin a 10 
per cent. solution of albumen increased 9 o cc. in volume, and an 
equally concentrated arabin solution 14 0 cc. ; while, inthe same — 
time, when the membrane was animal bladder or parchment, the 
endosmose was hardly perceptible (0'5 cc.). This shows that the — 
weak endosmotic action of colloids, when particular membranes 
are used, is not to be attributed to their weak attraction for 
water, but rather to the properties of the membrane. And in — 
the above case it appears that the different behaviour of the 
membranes corresponds to their different absorptivity for water. _ 
Especially does this appear from the fact that a very different 
endosmose takes place with one and the same membrane, accord- 
ing as it is employed as pyroxilin, or after its reduction as cellu- 
lose (by a process described in a previous part of the paper), 
Thus a 7 per cent. arabin solution received, through a pyroxilin 
membrane, 5'3 cc. water; when the membrane was reduced, an 
equally concentrated solution showed no endosmose, and a 9 per 
cent. solution of the same substance only received about o45 cc. 
water. of 
For substances largely soluble in water, the attraction of their 
particles to water may have wide limits of variation, according 
ae On 
* Abstract of 
part of apaper in “Poggendorff’s Annalen,” by J. 
Baranetzky, oan 
