The man’s work in connection with lead ceased from the time of the paresis, but some three years subsequently he died with cerebral hæmorrhage.
Portions of the organs, brain, kidney, liver, and spleen, were examined histologically, stained in the ordinary way with hæmatoxylin and eosin. In the brain the same marked microscopical hæmorrhages were observed as described in the previous case, and in addition many more areas of old fibroid scars, very minute, but apparently corresponding to earlier minute hæmorrhages. The kidney showed definite interstitial hæmorrhage (see [Plate III., Fig. 2]), as did the liver and spleen.
A portion of the brain was further submitted to chemical examination, and 0·0014 gramme of lead was determined as present.
The importance of this confirmatory evidence is undoubted, as the presence of the capillary hæmorrhage existing in the tissues of a person dying under suspicious circumstances when employed in a lead process is confirmed by the chemical determination of lead in the tissues.
The following tables, arranged under three headings, give some of the experimental results obtained by submitting animals to the effect of compounds of lead.
[Table XI.] gives the inoculation experiments.
The materials used in these experiments were those used in the inhalation and feeding experiments. The experiments are also arranged in such a manner that each series is a control one of the other.
The amount of substance used for the inoculation gives some rough idea of the dose required to produce poisoning in an animal; but even this question of dose in absolute quantities, administered hypodermically, shows considerable variation in the degree of poisonous effect. The first animal in [Table XI.] was inoculated with acetate, this being one of the more soluble lead compounds, and was given it in three small doses. The animal received 0·3 gramme per kilogramme of body weight, whereas in No. 35 2 grammes of washed frit—that is to say, lead glaze formed by fusing together litharge and silica—actually did produce symptoms, but of a mild nature. Animal No. 33 only had 0·16 gramme, being 0·05 gramme per kilogramme of body weight; and this caused acute symptoms. 0·35 gramme of white lead in a 3·500 kilogramme animal (No. 31) produced no symptoms at all. In the list of the inoculation experiments, three animals only exhibited no symptoms—one of these (No. 31) which was given white lead hypodermically, and Nos. 41 and 42, which were inoculated with lead silicate or lead frit, which had been previously treated with acetic acid or water.
Several practical points arise from these experiments, notably with regard to the frits, as it is seen that a considerable amount of the toxic properties contained in frit are removed by washing—most by washing with acetic acid and water, but also to some extent by washing with hot water alone, showing that in the ordinary production of lead frit for pottery purposes a certain amount of lead in a soluble condition as regards the body tissues was still present. This is no doubt entangled in the true silicates in the forms of oxides, or even as carbonate. Further, the toxicity of the lead compounds used may certainly be arranged in the order of their solubility with regard to the animal tissues, the acetate being the most poisonous, and the frit, when washed, the least; but unwashed frit, even in relatively small doses, may produce poisoning. This point is still further emphasized in [Table XIII.] Animal No. 42, four months after previous inoculation, showed no signs of poisoning. Lead nitrate in water was therefore given in quantities of 0·01 gramme per diem; one month later this animal developed poisoning.
[Table XII.] deals with the feeding experiments.