INORGANIC SUBSTANCES. Ill 



which was at one time maintained by Orfila to be constantly met with in bones. 

 That this statement was erroneous, has been fully proved by subsequent re- 

 searches ;* and it may be confidently asserted that the presence of arsenic in the 

 tissues can only be attributed to its introduction into the system in some special 

 mode. Even when minute doses of arsenic are introduced into the body, as by 

 the use of mineral waters, vinegar, &c., containing this substance, they are 

 speedily eliminated from it by the urinary secretion ; so that the metal does 

 not accumulate in the tissues. It is only when introduced more rapidly than 

 the system can carry it off, that it exhibits its deleterious effects upon the eco- 

 nomy, and that it is detectable in the solid tissues. Thus Dr. Letheby has 

 shown that poisonous doses of arsenic may be repeatedly administered to animals, 

 without the usual injurious consequences, if diuretics be given at the same time 

 so as to occasion an unusual activity in their elimination. When even a sin- 

 gle dose has been administered, however, sufficiently potent to occasion death, 

 arsenic may very frequently be detected in the liver and kidneys (the excreting 

 organs towards which it is specially determined), and sometimes also in the heart, 

 lungs, brain, and muscles. The frequent presence of Copper in the liver of 

 Man, and in the bile and biliary concretions, may now be regarded as a well- 

 established fact in Animal Chemistry ; but it is not hence to be concluded that 

 this metal is a normal constituent of his body. On the contrary, there is valid 

 reason to believe that, when introduced in small quantities, either by its presence 

 in the food or drink ingested, or by the accidental contamination of these by the 

 utensils employed in their preparation, copper is removed by the excretory ap- 

 paratus, the liver affording the special channel for its elimination. It is inte- 

 resting to remark that copper appears to be a normal constituent of the blood of 

 some marine Invertebrated animals (both Molluscous and Articulated), where 

 it seems to replace iron. 2 The presence of Lead in the tissues and fluids of the 

 Human body would seem to be far more frequent j yet it is not entitled to rank 

 as a normal component of the organism. Lead is pre-eminently cumulative in 

 its tendencies ; that is, when it has been introduced into the circulation in small 

 quantities, the excreting organs make little effort to remove it, and it is depo- 

 sited in the tissues. Thus it happens that the habitual ingestion of even very 

 minute quantities of this metal, will, if continued for a sufficient length of time, 

 give rise at last to the most severe symptoms ; and that the entire body seems 

 to be then charged with the poison, which may especially fix, however, upon 

 particular muscles, or groups of muscles, which it paralyzes, and in whose sub- 

 stance it is deposited in very sensible amount. In the treatment of such cases, it 

 is a matter of the greatest importance to obtain the elimination of the poison 

 through the excretory organs ; and it does not appear that either the liver or 

 the kidneys can be acted on for this purpose so effectually as the skin, through 

 which the lead may be drawn forth in large quantities by means of warm sul- 

 phurous baths. 3 That the kidneys, however, do serve as channels for its removal, 

 is proved by the detection of lead in the urine, by hydrosulphate of ammonia; 

 and it seems to be to its power of rendering lead soluble, and, at the same time, 

 to its stimulation of the kidneys to increased action, so as to eliminate the 



1 See the Report on this subject, made by a Committee of the French Institute in 1841. 

 The medical witness, however, who is called on to speak as to the presence of arsenic in 

 the tissues, may expect to be severely questioned as to this point by an opposing counsel, 

 and should be prepared with his negative evidence. 



2 It is affirmed by Millon, that copper may be detected in human blood ; but his con- 

 clusions have been controverted by Melsens. See "Ann. de Chim. et de Phys.," Sieme 

 ser. torn, xxiii. pp. 358-372. 



3 See a highly interesting case of Chronic Lead Poisoning, in which this remedy was 

 most effectually employed, in the "Dublin Quarterly Journal of Medical Science," vol. 

 vii. p. 415. 



