Journal of the Society of Arts 304, 17.9.1858
The following letter, addressed to the editor of the Daily News, and published in that paper on the 13th inst., has been forwarded to the editor of the Society's Journal by Dr. Halley: -
Sir, - In your number for the 1st of the present month, which I have only just had an opportunity of perusing, there is a leading article on the above subject, in which allusion is made to a statement of mine, the validity of which you assert to have been controverted by the experiments and opinion of Mr. Phillips, the chemist to the Board of Inland Revenue. May I crave the indulgence of your space whilst I correct a misconception into which that gentleman has fallen, and at the same time cindicate the correctness of my own assertation.
The only communication that I have yet made upon this subject was that contained in a letter to the [Time] of the 11th January last, a letter hastily written on the spur of teh moment, in reply to one by Mr. Fletcher, purposely condensed as much as possible, but containing a plain statement of facts as they occurred, with the simple view of warming others, and, if possible, to prevent the suffering I had myself undergone.
This letter was copied nearly entire into the number of the Pharmaceutical Journal for February last.
In the number of the Journal of the Society of Arts for the 27th August last, at page 606, Mr. Phillips, taking the report in the Pharmaceutical Journal, entirely misconceives, or at any rate misquotes, my statement, for he says: "It is stated that Dr. Halley, of Harley-street, had detected arsenious acid in the atmosphere of his study, the walls of which were covered with green paper, and that the test he employed was 'sheets of paper soaked in a solution of ammonio-nitrate of silver,' and that upon this paper were deposited numerous well-defined crystals of arsenious acid." This is not what I stated, and I am surprised that any chemist should place such a miscontruction upon the words I used. The merest tyro in chemistry should be perfectly aware that arsenious acid could not be so deposited. What I did state was this: "The air of teh room was next carefully tested (by means of sheets of paper soaked in a solution of the ammonio-nitrate of silver, a very delicate test of arsenic), and distinct crystals of arsenious acid, visible under a low power with the microscope, and sufficiently well defined and numerous to preclude the possibility of mistake, were obtained on two repeated and separate occasions." In writing to a non-professional journal I did not enter into every step of an analysis of a purely chemical nature, but gave the results of the experiment, merely indicating between brackets the key to the means used, that any chemist curious in the matter might repeat the experiment, filling up, of course, the blanks left in the description of the process. The obtaining of arsenious acid crystals was a positive and conclusive result - the fact - terminating the whole experiment, the commencement of which was the suspension in my room of sheets of paper soaked in the solution of ammonio-nitrate of silver, which in their turn were submitted to reduction, and so on to the result, the process being that known as Reinach's test.
But Mr. Phillips questions the fact of the crystals obtained being really those of arsenious acid; on the contrary, asserting that they were "more than probably" those of nitrate of silver. Without laying claim to any great knowledge of crystallography, which you assert is my presumption, it requires no great amount of acumen to distinguish between the decided octahedra of arsenious acid and the tabular plates of nitrate of silver, not to inention the impossibility of the resulting crystals in the experiment described being those of the latter substance.
Again, Mr. Phillips has misquoted my opinion as to the mode in which the arsenic is given off from the paper. I have not asserted, nor do I believe, that the arsenic contaminates the air in the form of arsenious acid. This is a very difficult point to determine, requiring more time and attention than I have had to spare from my professional avocations; but that, under certain circumstances, arsenic does contaminate the air of rooms covered with those papers to a most deleterious extent I firmly re-assert; and shall be most happy - I won't say convince, but - to show Mr- Phillips or any other chemist interested in the point the results of the experiments alluded to, upon which this opinion is founded.
And now, sir, in regard to the counter-experiments of Mr. Phillips and others, I am not prepared to explain in what manner, in every instance, they have failed to obtain similar results. It is not easy from mere description to judhe of an experiment involving minutiæ of manipulation; but knowing the quantites experimented with, and the very minute results I obtained - knowing also that those results would have been overlooked but for the use of the microscope, which Mr. Phillips, in common with many of his school, seems to disparage - I confess that his experimetns, although, I have no doubt ably and apparently impratially conducted, have in no way shaken my confidence in those alluded to in my letter, conducted as they were with the kind and able assistance of Mr. williams, of New Cavendish-street, a gentleman shose extensive experience as a wholesale manipulator is well known. The tests used were all prepared by him, and he kindly undertook many of teh minutiæ of the analysis. It is however but fair to state that in several similar experiments I failed to obtain similar results - showing that it is not all arsenically coloured papers that give off the poison, and this may explain why some persons have not suffered from inhabiting rooms so papered; but, on the oter hand, I re-asserts, for I known from personal experience and from numerous instances to my own knowledge well authenticated, that many persons have suffered from this cause.
Apologising for the unavoidable length of this communication,
I am, &c.,
Alexander Halley, M. D.
7, Harley-street, Sept. 11, 1858
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The following is the passage in the article from the Daily News of the 1st inst., referred to above: -
The old proverb, that a "little knowledge is a dangerous thing," if not to its possessor at least to others, has been well exemplified by some recent chemical investigations. The progress of chemistry of late years has been so rapid that its most enthusiastic students have had hard work to keep pace with its advance. It has accomplished such marvels, and shown such usefulness in improving the manufacture of so many of the conveniences and even necessaries of every-day life, that we have all learnt to treat the opinion of the chemist at least with respect, if not with something approaching the most profound deference.
If the chemist is to retain that position, he can only secure it by the name not being usurped by those who really have no title to it. Those who do assume a knowledge of the science must also be careful not to step beyond the legitimate conclusions of their analysis, or substitute imagination or presumptuous assertion for demonstration.
In the evidence given by Dr. Alfred Swaine Taylor before the Committee of the House of Lords, on the "Sale of Poisons Bill," he alarmed their Lordships by describing the injurious effects of paper-hangings coloured with the arsenite of copper. Knowing the reputation of Dr. Taylor as a chemist, we have felt very uncomfortable since when sitting in any room covered with pretty green paper - especially if a gas-light has been burning. Our terror seems to have been partly shared by the Commissioners of the Inland Revenne Department. Their new offices had been hung with the poisonous paper, chosen no doubt for its refreshing colour. Instead of at once tering down the obnoxious paper, they proceeded according to the customary rule of routine; their attention having been calle to the circumstance they directed Mr. Phillips, the Chemist to the Board, to investigate the subject, and report.
The devotedness of the Commissioners is most admirable. We can fancy the conscious sense of martyrdom wit which they [-at] environed with supposed arsenical atmosphere, while their chemist was preparing his Report. We knew not that we possessed a Board who would sacrifice their own health, rather that put the tax-payers to the expense of re-papering their offices. We congratulate them on the result of their officer's Report, and that they have now the pleasing assurance that their devotion has not filled their bones and livers with arsenic, to be produced by Professor Taylor, on some post-mortem, for the edification of a coroner and his jury.
Mr. Phillips set about the investigation in a very proper an sensible manner. Two small closets were papered with the suspected covering. No ventilation was allowed, save that admitted round the chinks of the doors. The air was thus necessarily longer in contact with the paper that it would have been in an ordinary room. Both closets were carefully closed for 72 hours, and in one a gaslight was kept burning 45 hours. The most delicate re-agents for testing the atmosphere of the closets were used without detecting the slightest trace of arsenic. It may be asked, then, how did these papers acquire so bad a name?
Las February a physician communicated to the Pharmaceutical Journal that he had detected arsenious acid in the atmosphere of his study, the walls of which were covered with green paper. The test he made use of for determining this fact was the hanging in his room "sheets of paper soaked in a solution of ammonia and nitrate of silver." After a time he found the paper covered with numerous well-defined crystals of arsenious acid, visible under a low power with the microscope. Mr. Phillips hung paper similarly prepared in his experimental closets. his paper was covered with crystals, but analysis proved these crystals to be composed of nitrate of silver, derived from the solution in which it had been dipped. Mr. Phillips therefore assumes, and we think with perfect justice, that if the learned Physician had trusted less to his presumed knowledge of crystallography, and tested his crystals, instead of jumpung at the conclusion that they were composed of arsenic, he would have found them nothing more than nitrate of silver.
It may be some consolation for those of our readers who inhabit rooms papered with pretty green patterns, to learn that Mr. Phillips and his family have occupied a sitting-room covered with a paper heavily laden with arsenite of copper, for three years, without experiencing the slightest ill effect, though his bed-room during the whole time was papered with arsenical hangings. This is not, however, the principal reason why we have noticed Mr. Phillips's admirable Report. It is, we conceive, of the greatest importance that the public should be put on their guard against the too easy reception of assumed chemical conclusions.
We have no doubt of the perfect good faith of the physician who called the attention of the public to his presumed discovery. He did so from a praiseworthy motive. But we hope the exposure of his defective analysis will caution others from intruding their imperfect determinations on the public, to the serious detriment, it may be, of their honest neighbours.
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The following letter, in reply to Dr. Hallery, appears in the same journal for the 14th inst.: -
To the Editor of the Daily News.
Sir, - Dr. hallery has endeavoured to show, that in your leading article on the hasty conclusions formed by some chemists you have done him an injustice. He believes that you have been misled by the report of Mr. Phillips, the chemist to the Board of Inland Revenue.
Now, sir, I do not believe that you have been misled in the slightest particular, or done any injustice to Dr. Halley. What are his own statements in defence of his analysis? He says that he tested the air of the room covered with arsenical dyed paper by means of sheets of paper soaked in a solution of the ammonio-nitrate of silver, that these sheets of paper, after exposure, were reduced, submitted to a test know by the name of reinsch, and that by this means he obtained crystals sufficiently large to be seen under a low power of the microscope.
Because these crystals were decided octahedra, he maintained that they were crystals of arsenious acid. You, sir, complain, and so do I, that because Dr. Halley saw crystals of the form assumed by arsenious acid under certain circumstances, he jumped at the conclusion that the form of the crystal was a sufficient evidence to identify the substance. Now, sir, I have devoted a little attention to the subject of crystallography, and I therefore know that there are a vast number of substances besides arsenious acid which will crystallise as regular octahedra. Dr. Halley had paper soaked in a combination of ammonia, silver, and nitric acid. He submits this paper, after its exposure to an atmosphere contaminated by gas, to certain tests. The paper had therefore, in all probability, absorbed the element of sulphur, either in a simple state or combined with certain gases. Can Dr. Halley, therefore, take upon himself to assert, that the octahedral crystals could not have been formed from certain chemical combinations made during his experiments, which may not have contained a single particle of arsenic or arsenious acid? Is he sure that these octahedra were not crystals of sal ammoniac?
His sheets of test paper contained ammonia, the paper itself was probably not free from the chlorine it had absorbed in its manufacture. Is it not therefore as probable that the crystals he saw under his microscope were a combination of chlorine and ammonia, which will assume the form of a perfect octahedron, as that they were formed from a combination of arsenic and oxygen derived from the atmosphere? Which is more probable? That the crystals were formed from the combination of substances supposed to be derived from the atmosphere. But taking into consideration the known impurities of the atmosphere, these might have combined with some of the ingredients contained in or introduced into the paper, so as to form combination, known to crystallise in the form of the regular octahedron.
For any evidence Dr. Halley has given us to the contrary, he may have actually produced diamonds without being aware of his valuable discovery. Both his paper and the atmosphere contained carbon. The diamond, as pure carbon, assumes frequently the form of the perfect octahedron, in its crystals. If form be a certain test as to chemical composition, what evidence had Dr. Halley adduced that his so-called crystals of arsenious acid may not have been microscopic diamonds.
Dr. Halley admits that he was satisfied that because he saw crystals which he assumed to be perfect octahedron, these crystals were necessarily composed of arsenious acid, because he suspected the presence of arsenic in the atmosphere. It is of his rash conclusion that Mr. Phillips complains. He examines the atmosphere of a room far more likely to be impregnated with arsenic than that examined by Dr. Hallery, without discovering the slightest trace of that deleterious substance. Mr. Phillips is a chemist, Dr. Halley a microscopist. Dr. Hallery gets a friend to manipulate the chemical part of his tests for him. Trusting to the deceptive form of his crystals, he neglects to submit these crystals to any test but this form. That form belongs to a host of substances [---] arsenious acid; therefore Dr. Halley's ambiguous [---] cannot be taken ans any confutation of Mr. Phillips's analysis.
Dr. Halley wrote his account of his experiments vaguely as to lead Mr- Phillips to infer, as one reasonably might have done, that the microscopical crystals were deposited on the surface of the test papers. Mr. Phillips found his paper covered with crystals of nitrate of silver, he, therefore, hazarded the opinion that Dr. Halley's crystals, if tested, would probably have been found to be simply nitrate of silver. To this Dr. Halley replies, that it requires no great amount of acumen to distinguish between the dediced octahedra of arsenious acid, and the tabular plates of nitrate of silver. If Dr. Halley will consult Phillips's translation fo the Pharmacopeia, which I have no doubt he possesses, he will see there that the author of that work states that the octahedral faces of crystals of the nitrate of silver sometimes are [---] englarged as nearly to obliterate the rhombic faces. It would require a very delicate eye to dintinguish the octahedra of nitrate of silver, with their upper and lower angles replaced by a plane, from the regular octahedra of arsenious acid, with their upper and lower angles replaced, as they frequently are, by planes of the cube.
Without actual goniometrical measurement, it is extremely difficult to distinguish the regular octahedron from some of the octahedra of both the square prismatic and the rhombic systems.
I would recommend Dr. Halley to repeat his experiments, and when he has obtained his octahedra, to sumbit them to such chemical tests as may satisfactorily determine their substance. Till he does so, he has no answer to Mr. Phillips's tests, nor will his negative crystalline evidence satisfy a
CRYSTALLOGRAPHER.
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