904 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[May 17, 1873. 
through the hydration of the starch and gluten. The 
proportions given are the result of numerous experiments. 
The saturated solution of nitrate of zinc is strongly 
caustic, and its coagulating property is intense. It is 
reported to have been successfully used in cauterizations 
by Dr. Clement, physician of the Hotel-Dieu, Lyons. 
Caustic Mixture of Nitrate and Chloride of Zinc. —Se¬ 
veral attempts were made to combine the nitrate and 
chloride of zinc in a paste that should possess the advan¬ 
tage of suppleness, and of not contracting when spread 
over a surface, which is characteristic of that prepared 
from the nitrate. Such a paste was obtained; it remained 
soft, spread easily, and did not contract; but in conse¬ 
quence of the avidity of the chloride for water, the slough 
produced by it has not proved so clean as that produced 
by the nitrate alone. The following is the formula:— 
Chloride of Zinc.50 grams. 
Nitrate of Zinc.100 „ 
Water.80 „ 
Dissolve by the aid of heat the chloride and nitrate of 
zinc in the water and allow the solution to cool, when it 
will have a density of about 1‘650°. 100 c.c. are then 
mixed with 75 grams of flour. 
PROFESSOR TYNDALL ON LIGHT.* 
(Concluded from p. 888.) 
One word more I should like to say regarding Eresnel. 
There are things better even than science. There are 
matters of the character as well as matters of the 
intellect, and it is always a joy to those who wish to 
think well of human nature, when high intellect and 
upright character are combined. They were, I believe, 
combined in this young Frenchman. In those hot con¬ 
flicts of the undulatory theory, he stood forth as a man of 
integrity claiming no more than his right, and ready to 
concede their right to others. He at once recognized and 
acknowledged the merits of Thomas Young. Indeed, it 
was he and his fellow-countryman, Arago, who first 
startled England into the consciousness of the injustice 
done to Young in The Edinburgh Revieio. I should like to 
read you a brief extract from a letter written by Fresnel 
to Young in 1824, as it throws a pleasant light upon the 
character of the French philosopher. “For a long time,” 
says Fresnel, “ that sensibility, or that vanity, which 
.people call love of glory, has been much blunted in me. 
I labour much less to catch the suffrages of the public 
than to obtain that inward approval which has always 
been the sweetest reward of my efforts. Without doubt, 
in moments of disgust and discouragement, I have often 
needed the spur of vanity to excite me to pursue my re¬ 
searches. But all the compliments I have received from 
Arago, La Place, and Biot, never gave me so much 
pleasure as the discovery of a theoretic truth, or the 
confirmation of calculation by experiment.” 
This is the core of the whole matter as regards science. 
It must be cultivated for its own sake, for the pure love 
of. truth, rather than for the applause or profit that it 
brings. And now my occupation is gone. Still I will 
bespeak your tolerance for a few concluding remarks in 
reference to the men who have bequeathed to us the vast 
body of knowledge of which I have sought to give you 
some faint idea in these lectures. What was the motive 
that spurred them on? What the prize of their high 
calling for which they struggled assiduously ? What 
urged them to those battles and those victories over 
reticent Nature which have become the heritage of 
the human race ? It is never to be forgotten that not 
one of those great investigators, from Aristotle down to 
Stokes and Kirchhoff, had any practical end in view, 
according to the ordinary definition of the word “ prac- 
# Abstract of a series of lectures delivered in the Cooper 
Institute, New York, and reported in the New York 
lnbune. 
tical.” They did not propose to themselves money as an 
end, and knowledge as a means of obtaining it. Tf™ 
most part, they nobly reversed this process? made know¬ 
ledge their end, and such money as they possessed the 
means of obtaining it. We may see to-day the issues of 
their work in a thousand practical forms, and this may be 
thought sufficient to justify, if not to ennoble their efforts. 
But they did not work for such issues ; their reward was 
of a totally different kind. In what way different ? We 
love clothes, we love food, we love fine equipages, we love 
money, and any man who can point to these as the 
result of his efforts in life justifies those efforts before all 
the world. In America and England more especially he 
is a practical man. But I would appeal confidently to this 
assembly whether such things exhaust the demands of 
human nature ? Given clothes, given food, given carriages, 
given money—is there no pleasure beyond what these can 
cover which the possessor of them would still covet ? I 
need not tell such an assembly that there are joys of the 
intellect as well as joys of the body, or that these pleasures 
of the spirit constituted the reward of our great investi¬ 
gators. Led on by the whisperings of natural truth, 
through pain and self-denial, they often pursued their 
work. With the ruling passion strong in death, some of 
them, when no longer able to hold a pen, dictated to their 
friends the results of their labours, and then rested from 
them for ever. 
Could we have seen these men at work without any 
knowledge of the consequences of their work, what should 
we have thought of them ? To many of their cotempo¬ 
raries it would have appeared simply ridiculous to see 
men whose names are now stars in the firmament of 
science straining their attention to observe an effect of 
experiment almost too minute for detection. To the un¬ 
initiated they might well appear as big children playing 
with not very amusing toys. It is so to this hour. Could 
you watch the true investigator—your Henry or your 
Draper, for example—in his laboratory, unless animated 
by his spirit, you could hardly understand what keeps 
him there. Many of the objects which rivet his atten¬ 
tion might appear to you utterly trivial; and, if you were 
to step forward and ask him what is the use of his 
work, the chances are that you would confound him. He 
might not be able to assure you that it will put a dollar 
into the pocket of any human being living or to come. 
That scientific discovery may put not only dollars into the 
I pockets of individuals, but millions into the exchequers 
of nations, the history of science amply proves ; but 
the hope of its doing so is not the motive power of the 
investigator. It never can be his motive power, 
I know what De Tocqueville says of you. “ The man of 
! the North,” he says, “has not only experience, but know¬ 
ledge. He, however, does not care for science as a plea¬ 
sure, and only embraces it with avidity when it leads to 
useful applications.” I wonder whether the great histo¬ 
rian and analyst of democratic institutions would repeat, 
these words to-day ? What are useful applications ? In 
man’s body alone to be the object and arbiter of what is. 
useful ? Is there no nakedness of the mind to be clothed 
as well as nakedness of the body ?—no hunger and thirst 
of the intellect to satisfy ? Surely no two terms were 
ever so much distorted and misapplied with reference to 
man in his higher relations than these terms useful and 
practical. Let us expand the definitions of these terms 
until they embrace all the needs of man, his highest intel¬ 
lectual needs inclusive. It is specially on this ground of 
its administering to the higher needs of the intellect ; it 
is mainly because I believe it to be wholesome as a source 
of knowledge, and as a means of discipline, that I urge 
the claims of science upon your attention. 
But with reference to material needs and joys, surely 
pure science has also a word to say. People sometimes 
speak as if steam had not been studied before James Watt, 
or electricity before Wheatstone and Morse, whereas, in 
point of fact, Watt and Wheatstone and Morse, with all 
their practicality, were the mere outcome of antecedent 
