Additional remarks on active molecules / by Robert Brown.

  • Robert Brown
Date:
[1829]
Catalogue details

Licence: Public Domain Mark

Credit: Additional remarks on active molecules / by Robert Brown. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Although I endeavoured strictly to confine myself to the statement of the facts observed, yet in speaking of the active Molecules I have not been able, in all cases, to avoid the introduction of hypothesis; for such is the supposition, that the equally active particles of greater size, and frequently of very different form, are primary compounds of these Mole- cules,—a supposition which, though professedly conjectural, I regret having so much insisted on, especially as it may seem connected with the opinion of the absolute identity of the Molecules, from whatever source derived. On this latter subject, the only two points that I endea^ voured to ascertain, were their size and figure: and al- though I was, upon the whole, inclined to think that in these respects the Molecules were similar from whatever sub- stances obtained, yet the evidence then adduced in support of the supposition was far from satisfactory; and I may add, that I am still less satisfied now that such is the fact. But even had the uniformity of the Molecules in those two points been absolutely established, it did not necessarily follow, nor have I any where stated, as has been imputed to me, that they also agreed in all their other properties and functions. I have remarked, that certain substances, namely, sulphur, resin, and wax, did not yield active particles, which, how- ever, proceeded merely from defective manipulation; for I have since readily obtained them from all these bodies : at the same time I ought to notice that their existence in sulphur was previously mentioned to me by my friend Mr. Lister. In prosecuting the inquiry subsequent to the publication of my Observations, I have chiefly employed the simple micro- scope mentioned in the Pamphlet, as having been made for me by Mr. DoUond, and of which the three lenses that I have generally used, are of a 40th, 60th, and 70th of an inch focus. Many of the observations have been repeated and con- firmed with other simple microscopes having lenses of similar powers, and also with the best achromatic compound micro- scopes, either in my own possession or belonging to my friends. The result of the inquiry at present essentially agrees with
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