§ 894. Effects.—All the salts of thallium are poisonous. One of the earlier experimenters on the physiological action, Paulet, found 1 grm. (15·4 grains) of thallium carbonate sufficient to kill a rabbit in a few hours; there were loss of muscular power, trembling of the limbs, and death apparently from asphyxia. Lamy[973] used thallium sulphate, and found that dogs were salivated, and suffered from trembling of the limbs, followed by paralysis. The most definite results were obtained by Marmé,[974] who found that ·04 to ·06 grm. of a soluble thallium salt, injected subcutaneously or directly into the veins, and ·5 grm. administered through the stomach of rabbits, caused death. The action is cumulative, and something like that of mercury: there are redness and swelling of the mucous membrane of the stomach, with mucous bloody discharges; hæmorrhage may also occur from the lungs. Thallium is eliminated through the urine, and is also found in the fæces; it passes into the urine from three to five minutes after injection: the elimination is slow, often taking as long as three weeks. It has been found in the milk, in the tears, in the mucous membrane of the mouth, of the trachea, in the secretion of the gastric mucous membrane, and in the pericardial fluid; and in these places, whether the poison has been introduced by subcutaneous injection, or by any other channel. It seems probable that the reason of its being detected so readily in all the secretions is the minute quantity which can be discovered by spectroscopic analysis.
[973] Chem. News, 1863.
[974] Göttinger Gelehrt. Nachrichten, Aug. 14, No. 20.
§ 895. Separation of Thallium from Organic Fluids or Tissues.—The salts of thallium, if absorbed, would only be extracted in traces from the tissues by hydrochloric acid, so that, in any special search, the tissues are best destroyed by either sulphuric or nitric acid, or both. In the ordinary method of analysis, when an acid liquid is first treated with sulphuretted hydrogen, and then made alkaline by ammonia and ammonic sulphide, thallium would be thrown down with the manganese and iron of the blood. From the mixed sulphides, thallium may be separated by oxidising and dissolving the sulphides with nitric acid, evaporating off the excess of acid, dissolving in a very little hot water, and precipitating thallous chloride by solution of common salt. The ease, however, with which thallium may be separated from solutions of its salts by galvanism is so great as to render all other processes unnecessary: the best way, therefore, is to obtain a deposit of the metal on platinum by a current from one or more cells, and then to examine the deposit spectroscopically. Thallium gives, when heated in a Bunsen flame, a magnificent green line, the centre of which corresponds with wave length 534·9; a second green line, the centre of which coincides with W.L. 568, may also be distinguished.
4. ALUMINIUM.
§ 896. Aluminium and its Salts.—A strong solution of acetate of alumina has irritant properties, and has given rise to accidents. The term alum, in a chemical sense, is given to a class of bodies of the type of AlKSO4. Common alum is at the present time ammonia alum, NH4Al(SO4)2 + 12H2O; when made anhydrous by heat it is known by the name of burnt alum, and possesses caustic properties.
§ 897. Action of Alum Salts.—Death or illness has hitherto only taken place from the ingestion of large doses of alum or the acetate, and the symptoms in these cases have been those of an irritant poison; we are, however, indebted to Paul Siem[975] for a research on the absorbed substance, in which the local effects as far as possible have been reduced.