From Edward Frankland   Jan. 22/57

Owens College | Manchester Jan. 22/57

My dear Tyndall

You request to have my opinion respecting Bunsen’s contributions to science;¹ it is with much pleasure that I give it you, although I feel that any brief sketch of mine can convey only a very imperfect idea of the merits of researches so extensive and embracing so many departments of chemical and physical science, as those for which we are indebted to Bunsen.

In addition to numerous other researches, I may mention the following as highly valuable contributions.

1. Researches on Cacodyl (numerous memoirs)²

2. A new system of gaseous analysis (contained in numerous memoirs)³

3. Researches on the gases evolved from blast furnaces⁴ with suggestions for the useful application of those gases.

4. Researches on the Volcanic Phenomena of Iceland.⁵

5. On an improved method for the determination of nitrogen in organic compounds.⁶

6. Researches on chemical affinity.⁷

7. On a new, cheap & powerful galvanic battery.⁸

8. Bunsen & Berthold on hydrated peroxide of iron as an antidote for Arsenic.⁹

Of the researches on Cacodyl it is impossible to speak too highly. From whatever point of view we regard them, they cannot fail to excite our admiration. The difficulty & danger attending the manipulations with those spontaneously inflammable and highly poisonous volatile bodies, which once nearly occasioned fatal results to the operator, are almost, I may even say quite, unparalleled; especially when we consider the singular perseverance with which the subject was followed out into its most minute ramifications. Further, the accuracy of the results of these researches has been fully established by later investigations; for, although at the time Bunsen’s researches were made, none of the generalisations, which have sprung from more recent researches on Organo-metallic bodies, could assist the experimenter in determining rational formulae, yet in no single instance has any formula, he then established, since been found to be incorrect. Finally the results of the investigation were of immense importance to science. The beneficial influence which the discovery of Cacodyl has exerted upon the development of sound views in organic chemistry, and the pursuit of rational paths of research, can scarcely be over estimated, since the support which it gave to the theory of compound organic radicals, enabled that theory to exist and to bring forth abundant fruits, throughout a period in the history of the science when there was but feeble evidence of its truth, and until the researches, both of supporters and antagonists, finally established the fundamental accuracy of that theory.

The importance of Bunsen’s contributions to gaseous analysis is well known to all chemists. Previous to his labours in this field, eudiometrical determinations¹⁰ were of a very crude and unsatisfactory character; but his improvements in the construction of eudiometers¹¹ enabled every operator to construct these instruments for himself with facility, and possessing an accuracy of measurement which could not be exceeded in the workshop of the philosophical instrument maker. These improvements, together with his new methods of applying absorbents to gaseous mixtures, have imparted to eudiometrical determinations a degree of accuracy never exceeded and rarely equalled in other departments of analytical chemistry. It is also perhaps worthy of notice that the subsequent improvements in gaseous analysis have been chiefly if not entirely made by the pupils of Bunsen. (Regnault for instance received special instruction in gas analysis from Bunsen).

The researches on gases evolved from blast furnaces consuming charcoal, coke,¹² and coal, the latter made in conjunction with Lyon Playfair, are masterly specimens of experimental skill and analytical accuracy, and have led to important applications of the waste gases from such furnaces to useful purposes; as for instance at Swansea,¹³ to the heating of steam boilers, and in Germany, to the puddling of iron.¹⁴

Bunsens investigations into the volcanic phenomena of Iceland I need not further allude to, as you are much better acquainted with their peculiar merits than I am, and therefore I will only remark on this head, that they exhibit in a high degree, the combination of acute inductive reasoning with great manipulatory resources.

His mode of determining nitrogen in organic compounds, although somewhat difficult of execution, is undoubtedly one of the best methods known, and, with very few exceptions, it is applicable to every organic compound containing that element.

His researches on chemical affinity open up a new path of enquiry which must yield invaluable results, in fact there can be little doubt, that much of the future of chemistry is most intimately connected with such numerical expressions of the forces engaged in the production of chemical phenomena.

You are yourself intimately acquitted with the working of Bunsen’s Carbo-zinc Battery and therefore any remark of mine, on this head, would be quite superfluous.

With regard to the employment of hydrated peroxide of iron as an antidote for arsenic,¹⁵ I must refer you, for its value, to your medical friends. I believe this antidote is now almost universally employed in Germany, and with perfect success, provided it be administered before much of the poison has been absorbed into the system.

In conclusion, it is my deliberate conviction, that even the researches upon Cacodyl taken alone, place Bunsen in the very highest position amongst the cultivators of natural science, and that those researches are, for the reasons already stated, unsurpassed in merit by any others with which chemical science has been enriched.

Believe me, my dear Tyndall | ever yours sincerely | E. Frankland.

RI MS JT/1/F/46