(Carbon Monoxide, Chlorine). Irritant poisons, when taken in ordinary doses, occasion speedily violent vomiting and purging, preceded, accompanied, or followed by intense pain in the abdomen, commencing in the region of the stomach. The corrosive poisons, as distinguished from those in a more limited sense termed irritant, generally produce their results more speedily, and give chemical indica- tions; but every corrosive poison acts as an irritant in the sense here adopted. Narcotic poisons act chiefly on the brain or spinal marrow. Either immediately or some time after the poison has been swal- lowed, the patient suffers from headache, giddiness, paralysis, stupor, delirium, in- sensibility, and, in some instances, convul- sions. The effects of one class are, however, sometimes produced by the other,-more commonly as secondary, but sometimes even as primary symptoms. The evidence of poisoning as derived from symptoms is to be looked for chiefly in the suddenness of their occurrence; this is perhaps the most reliable of all evidence derived from symptoms in cases of criminal poisoning; see Taylor, Pois. 107; Christi- son, Pois. 42; though none of this class of evidence can be considered as furnishing anything better than a high degree of probability: the regularity of their in- crease; this feature is not universal, and exists in many diseases; uniformity in their nature; this is true in the case of comparatively few poisons; the symptoms begin soon after a meal; but sleep, the manner of administration, or certain dis- eases, may affect this rule in the case of some poisons; when several partake at the same time of the same poisoned food, all suffer from similar symptoms; 2 Park. C. C. 235; Taylor, Pois. 118; the symptoms first appearing while the body is in a state of perfect health; Archb. Cr. Pl. Water- man ed. 948. Appearances which present themselves on post-mortem examinations are of impor- tance in regard to some classes of irritant poisons; see The Hersey Case, Mass. 1861; Palmer's Case, Taylor, Poisons 697; 17 Am. L. Reg. N. S. 145; but many poisons leave no traces which can be so discovered. Chemical analysis often results in im- portant evidence, by discovering the pres- ence of poison, which must then be ac counted for; but a failure to detect it by no means proves that it has not been given. Christison, Poisons 61, 62. The evidence derived from circumstances differs in nothing in principle from that in case of commission of other crimes. Homicide by poisoning is generally either accidental, so as not to amount to murder, or deliberate: yet it has been held that there may be a verdict of murder in the second degree under an indictment for poisoning; 19 Conn. 388. The doctrine of principal and accessory is also modified to some extent in its application to cases of poisoning; 2 Mood. Cr. Cas. 120; 9 C. & P. 359; 9 Co. 81. To constitute an adminis- tering of poison, it is not necessary that there should be a delivery by hand; 4 С. & P. 356; 1 Bish. Cr. L. § 651. Intent to kill need not be specifically alleged in an indictment for murder by poison; 1 Fast, Pl. Cr. 346, 3 Cox. С. С. 300; 8 C. & P. 418; 2 Allen 173. Where a wholesale dealer supplied a poisonous drug in place of a harmless drug ordered, he was held liable in damages to the cus- tomer who bought it from the retailer and suffered injury from taking it; 6 N. Y. 397. Many of the states have statutes inflict- ing severe penalties upon the administer- ing of poisons with a malicious intent. See Archb. Cr. Pr. Waterman's ed. 942; 86 Va. 223. Practicing physicians, who are graduates of a medical college, are competent to tes- tify as experts on the subject of arsenical poisoning, although it is not shown that they have had actual experience in poison cases; 143 Ill. 571. Consult Christison, Taylor, Blyth, Poi- sons; Beck, Taylor, Wharton & Stillé, Witth. & Beck, Clevenger; Med. Jur.; Archbold, Crim. Pract. Waterman's ed.; Russell, Crimes; Wharton, Homicide. See