Manchester May 2. 1827
My dear Sir
I beg you to accept my best thanks for the obliging present of your work on Chemical Manipulation1, which I shall value, not only for its intrinsic merits, but as a mark of your friendly regard. I have already perused the greater part of it, and find that it abounds with matter of the greatest use to all who embark in operative chemistry, conveyed too in a manner which is distinct and intelligible without being tediously minute. At this day, when every thing that is valuable in Chemistry depends on the most rigid accuracy, he who points out how that accuracy may be obtained, and warns against the many fallacies that may creep unsuspected into experiments intended to be correct, renders an essential service to Science, a service little short of that which is conferred by the discovery of new facts. In looking back upon my own experiments, I can remember the time when a work, accented as your’s is, would have been quite invaluable to me, and would have saved me many disappointments and much labour, spent amiss from imperfect instruments; and even now, I note many things which, if I ever again undertake a regular train of experiments, will greatly facilitate my operations. One or two trifles have occurred, in which I prefer my own mode of working, but they are not worth writing about, and can be mentioned when we meet. The method of graduating tubes (p.77) I have long used, and have thus at little trouble got a stock which could not have been made by weighing, without a great waste of time. The inclosed little paper2 describes the method, but I have for many years used, with you, fractional parts of a cubic inch.
In various manipulations with Gases I find great advantage in the use of caoutchouc bottles, especially when the absorption of any portion of a gas renders them preferable for the reasons assigned at page 3 of my little paper. For instance in washing out carbonic acid from any gas on which liquid potash does not act, I use an apparatus similar to fig. 3 with the pencilled addition. The pencilled globe being filled with the gas, its neck is inserted into the short bit of tube, ground within to fit it, to which the elastic bottle is fixed. Removing this last from beneath the water of the trough, and inverting it, the gas and liquid may be agitated together, the sides of the bottle collapsing as the absorption goes on. The disunion is made under water which rushes into the bottle, while by good management the liquid which remains in the globe may be kept there, without contaminating the water of the trough. If one operation be insufficient, it may be repeated; and it will be found useful to vary the relative proportions between the elastic bottle and the globe, to suit cases in which a large or a small proportion of the gas is absorbable.
With sincere esteem and regard, I am, | Dear Sir | Yours very faithfully | W. Henry.
P.S. I had very lately, from a friend, a statement in conversation of some facts which since before unknown to me. They will induce me to alter the last par on page 137 of my book (vol 1, 10th ed) if an opportunity should be given me leaving out “undertaken” and the seven following words3.
I must not omit to thank you for copies of several interesting papers from the Phil. Trans. They will always reach me safely if sent to Longman’s PNR4 who correspond with my bookseller here.
M. Faraday Esq
Address: M. Faraday Esq
HENRY, William (1813): “Description of an Eudiometer, And of other Apparatus employed in Experiments on the Gases”, Mem. Lit. Phil. Soc. Manch., 2: 384-90.
HENRY, William (1826): The Elements of Experimental Chemistry, 10th edition, 2 volumes, London.
HENRY, William (1829): The Elements of Experimental Chemistry, 11th edition, 2 volumes, London.
WALLIS, Philip (1974): At the Sign of the Ship: Notes on the House of Longman, 1724-1974, Harlow.
Please cite as “Faraday0324,” in Ɛpsilon: The Michael Faraday Collection accessed on 27 April 2024, https://epsilon.ac.uk/view/faraday/letters/Faraday0324