Minutes of evidence and appendices. Vol. 2, Evidence received in 1902-3, together with appendices 16 to 32, and index (Being part 2 of the Final report of the Commission) / Royal Commission on Arsenical Poisoning arising from the consumption of beer and other articles of food or drink.

  • Great Britain. Royal Commission on Arsenical Poisoning.
Date:
1903
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Licence: Public Domain Mark

Credit: Minutes of evidence and appendices. Vol. 2, Evidence received in 1902-3, together with appendices 16 to 32, and index (Being part 2 of the Final report of the Commission) / Royal Commission on Arsenical Poisoning arising from the consumption of beer and other articles of food or drink. Source: Wellcome Collection.

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    A. Angell. | Mar. 1902. ype ot larsh mirror btained epends upon eid used. wamanageable ; this can be avoided by first gently heat- ing the plant or seeds in dilute acid for some hours in an open beaker and subsequently filtering. 8481. Have you compared the mirror formed when you use sulphuric acid and when you use hydrochloric acid ? —I find no difference. _ 8482. I think Dr. McGowan has found in experiments for us, and perhaps Mr. Hehner has also found, that a mirror when sulphuric acid is used is not comparable with that from hydrochloric acid?—Do you know the meaning of the word comparable in that instance ? (Dre M cGowan’) We have so far always used the sul- phurice acid mirror until quite recently, but the hydro- chloric acid mirror seems to be of a different type, and I should say rather more marked than the sulphuric acid mirror. Ihave not had much experience yet of the hydrochloric acid, but it strikes me it is rather more marked, so far as my experience goes. (Witness.) I have not noticed that. (Chairman.) You can get a good mirror with one or the other? (Dr. McGowan.) You can get a good comparable mirror with one or the other. I[ think the hydrochloric acid is rather the more delicate. (Witness.) I think I would agree to that last remark that it is rather more delicate if anything. (Sir William Church.) I gather that you mean hydro- chloric acid mirrors ought to be compared with hydro- chloric acid mirrors, and sulphuric acid mirrors com- pared with sulphuric acid mirrors, but that being done eliminary atment of ant bstance. (Dr. McGowan.) It is a matter of personal taste really, (Witness.) I agree with that. 8483. (Chairman.) In your determination of arsenic in superphosphate introduced directly into the apparatus? —Yes. _ 8484. Was there no interference with the test from any small quantities of organic matter in solution ?— No, not in the case of superphosphates, no interference. 8485. Were precautions taken to prevent any arsenic getting accidentally on to the leaves of the growing plants? Was there any wind ?—The danger was the in- troduction of arsenic either carried by wind or the splashing of rain, or otherwise, on the surfaces of plant or leaves. That was a source of danger, and we kept it before us the whole time. 8486. Did you use any precautions to prevent it, or wash off the arsenic?—We washed all the plants and all the parts of plants carefully in every instance. 8487. In your use of the Hehner-Marsh method what kind and size of drying tube for the escaping hydrogen was used?—The drying tube was 14 inches in length and five-eighths in diameter. The -nirror tube was five- sixteenths outside diameter, and about nine or ten inches long. 8488. What length of chloride of calcium did you have in the drying tube ?—Rather more than half the entire length; that would be seven inches. 8489. In fragments, small lumps ?—Yes, calcined and in fragments. 8490. Does your use of the Hehner-Marsh method in- volve any treatment of the leaves, seeds, etc., before Marshing ?—Usually it was better to cut up the pieces of plant or crush the seeds, and gently heat them in an open beaker with a little acid with them. That was my usual plan. It did away witha good deal of the danger of foaming in the flask. 8491. Did you use the whole liquid and solid together, or filter ?—In some instances it was necessary to filter, but if it was a thing you could pulp down sufficiently to get through, I preferred not filtering. 8492. Why did you prefer not to filter ?—Because some of the arsenic would be probably left in that por- tion which was upon the filter. 8493. If there was no previous treatment of the leaves and so on, were estiniations made with the same samples after the destruction of the organic matter? If you did not treat previously, did you take any means to destroy the organic matter before Marshing?—In most in- stances, it was not necessary. The result of maceration was sufficiently free from organic matter to permit the 4576, it done?—I do not think it is necessary with these vegetable infusions to destroy the organic matter. 8495. Did you never destroy the organic matter ?-— Not entirely. 8496. What quantities of the samples did you employ ? we took rhubarb stems, that is the leaf stems of the rhubarbs used for feeding purposes. We took 50 grammes and boiled in dilute hydrochloric acid, and from that we obtained a slight trace of arsenic. periments in each case ?—In each case, right through. 8498. Did you get any appreciable evolution of sul- phuretted hydrogen along with the arseniuretted hydro- gen ?—In one or two instances only, not as a rule, but where it occurred it was picked up by the lead paper. 8499. Assuming no previous treatment of the sample in a sufficient number of cases, when the sample yielded no arsenic, did you make a control experiment with an- other similar sample and a given small amount of arsenic?—No, That is to say did I ever introduce arsenic to prove that if it had been there I should have found it? 8500. Yes?—-No. I have done this in a certain way. It has happened that a negative result has been ob- tained from a quantity of a non-arsenicated plant or substance, and then afterwards my son, to corroborate what I have done before, with a portion of rhubarb stem in which we had found arsenic, has gone on with the experiment in which I found none by adding some of the arsenicated rhubarb, and then has got his mirror. That therefore is something of the same sort. 8501. Did you ever recover the whole of the arsenic that was added in any one of your experiments in which a known quantity of arsenic was put in ?—That could be only in the case where I tested my manure. I could not expect in any way to get back again the arsenic I had put into the soils quantitatively. 8502. Did the organic matter in the flask retain any portion of the arsenic so far as you know ?—Not so far as I know. I found it was extremely slow in coming off ; extremely tardy. So that it was a question some- times of hours before the last trace of arsenic came off if there was a thick foam forming on the surface of the boiling flask. I take it the bubbles contained arseniuret- ted hydrogen; and therefore as long as any of that foam was there there was danger of arsenic in the flask, so I continued until I had boiled it out. 8503. There is a prevalent idea, [ believe, that organic matter may seize hold of the arsenic and prevent it going away in the Marsh test ?-—-Retaining the whole of the arsenic present ? 8504. No, keeping a part of it?—I think that is pos- sible, but I have not had experience of that. 8505. Did you ever allow the blank to run over the same length of time as was taken up for that actual estimation ?—Yes. I have allowed it to run to the point of absolute total exhaustion; that is to say, until the whole of the hydrogen has come away, simply for a blank experiment. 8506. Did you ever obtain any false mirror—one that was carbonaceous ?—No. I know nothing of that. I have seen a slight discolouration which has led one to suspect a mirror was about to be formed, but I have never had a case where it was not sufficiently decisive if you actually got arsenic to be able to detect the fact. 8507. Were the solutions and extractions reduced to the arsenious state before Marshing?—No steps were taken before the liberation of the hydrogen to reduce it. The question, I think, means this: were any steps taken to reduce a possible arsenic compound to the arsenious state before its introduction into the flask ? 8508. Yes?—The answer is no. 8509. Has it been ascertained that the whole of a given quantity of arsenic acid would be reduced and deposited in fifteen minutes ?—Although fifteen minutes is the time that we give as being in most instances sufficient, we have never confined ourselves to a rigid line about time. As long as there was the slightest evidence of further deposit we would go on; and in some instances it was a very long time indeed. 8510. It would be very interesting to understand what degree of confidence may be placed in results in which the answer is negative, “ No arsenic mirror discovered ” ? -- I see the importance of the point. B Mr. A. Angell. 7 Mar. 1902. Jzganie matter was not entire .y destroyed before Marshing,. Control and blank experi« ments, and their ufficiency. bees a