4. _Arsenic sometimes exists naturally in the human body._—This startling proposition was first advanced by M. Couerbe, and by Professor Orfila soon afterwards.[545] The latter subsequently stated, that it exists only in the bones, and not in any of the soft solids.[546] It is now clear, however, that both of these experimentalists must have committed an error. Orfila himself admits that his early researches are vitiated by the subsequent discovery of arsenic in some kinds of sulphuric acid;[547] and all recent attempts by others to obtain his results have failed. Thus MM. Flandin and Danger could not detect arsenic in any part of the human body, when it had not been administered:[548] Pfaff was unable to detect an atom of it in the bones of man or the lower animals by Orfila’s own process:[549] Dr. Rees was equally unsuccessful:[550] and in 1841 a committee of the French Institute, who superintended the performance of an analysis in three cases by Orfila, reported that he failed in every instance to find a trace of arsenic, by a process which could detect a 65th part of a grain intentionally mixed with an avoirdupois pound of bones.[551] There is the strongest possible presumption, therefore, that human bones never contain any arsenic. And besides, supposing they did, the source of fallacy would be utterly insignificant; for, when it becomes necessary to search for arsenic absorbed into the textures of the body, it is never necessary to have recourse to the bones. 5. _Arsenic may exist in the soil of churchyards._—This proposition too was first announced by Professor Orfila, who found a little in the churchyard of Villey-sur-Tille, near Dijon, and of the Bicêtre, Mont-Parnasse, and New Botanic Garden at Paris.[552] And although MM. Flandin and Danger afterwards denied they could ever find any,[553] a committee of the Parisian Academy of Medicine reported that Orfila proved before them the accuracy of his statement.[554] But the arsenic exists in a state in which it cannot be dissolved out by boiling water: It has been hitherto separable only by boiling the churchyard mould with concentrated sulphuric acid. Hence it cannot pass by percolation through a coffin into a body; and consequently it becomes a source of fallacy only when the coffin has been broken up in the course of time, and the mould lies in actual contact with the organs to be analysed.[555] It plainly appears, then, that most of the fallacies alleged against the validity of the evidence derived from the discovery of arsenic within the human body in cases of poisoning have no real existence; and that those which are real can easily be provided against by simple and obvious precautions. 3. _Arsenite of Copper_.