. John M. Orr, esq., made the opening state moot bef ore the jury* He-commenced by making some general observations upon the solemn duties of juries, and especially of a jury trying a case so serious'in its nature as this. Mr. Orr then stated the main facts of the case, On the 22d of March last, the prisoner, Mrs. Lloyd, was living in a small house in the city, with the child. Maud', three years of age, and a colored servant, Delphi, who was much attached to both of them. The child was taken ill, and and in forty-eiffht hours she was dead. The child's guuardian, Mr. Orrison, suggested to Mrs. Lloyd the propriety of an investigation of the cause of death, but site declined until Mr. Orrison insisted upon it, and a jury of inquest was held, and a post-mortem examination was made. The stomach of the child was taken out and placed in possession of Recorder Bentley, who ha* since.died, and tho Commonwealth cuu follow that stomach no longer, and the analysis of it was not admitted as evidence. The jury of the county found au indictment against her for murder. She appeared before the County Court and elected to be tried in this, the Circuit CourL The case has passed all these ordeals, every oue of which is imposed by the law as a barrier against hasty accusations. The charge was that Mrs. Lloyd administered arsenic to her little daughter Maud, thereby poisoning her. The first inquiry was did ehe die of arsenical poisoning; ana the second was. who administered that deadly drug? Mr. Orr addressed himself to the symptoms of the fatal sickness of the child, and the history of that sickness. Dr. Mott did not suspect poison, and thought death had resulted from intense congestion of the stomach; but when the stomach was taken out and held to the light, he saw that there was no trace of that disease.— Mr. Orr next read from “Taylor on Poisons,” jn regard to the symptoms of arsenical poisoning, and dwelt upon their resemblance to the symptoms of Maud Lloyd’s last illness. Of the identity of tho child's body the jury could have no doubt, and the testimony on that point had been sufficient. Prof. Tonry got from the liver, kidneys and spleen eight-tenths of a grain of arsenic, and he knew, from previous tests, that no trace of arsenic was in any of the chemicals used. Prof. Woruily had come from Ohio, and Prof. Mallet from the University of Virginia, and both endorsed Prof. Toury's process and his weights. The jury had then the definite report of Prof. Tonry, aod his endorsement by Profs. Wormley and Mallet, and, on the other side, was only the indefinite statement of three inexperienced persons. Mr. Orr read from Taylor ou poisons, in reference to the finding of a residue of arsenic in the stomach; he then read from Christison, in reference to the value of the discovery of arsenic, and said that in this case there was no doubt about the presence of arsenic, and the only question raised was as to quantity. Ifthe defence charge that arseuio was ip thooarbolate of lime used as a disinfectant, they should have tested it, as they did the bismuth. The burden was uqon the defence to prove that arsenic was in the carbolatc of limo and their failure to make the attempt showed that they did not believe there was any arsenic in it. The de-feu ce allege that they found arsenic in the bismuth, ftiul claimed that they got larger spots than those shown by Prof. Tonry. So attempt was made to measure the quantity of arsenic in those spots. Then, too, there is the remarkable fact that bismuth, in which Prof. Tonry could find no arsenic, and which has been often and recently prescribed without any deleterious effects following, the experts for the defence claimed to contain arsenic in it, and had asserted it positively. The State could not wring out of the experts for the defence an estimate of the quantity of arsenio in the spots they exhibited, and the highest quantity of arsenic known to have been discovered in bismuth is one-sixth of one per cent., and Prof. Wormley had so stated. That same bismuth had been tested and used previously without giving any trace of arsenic, and the whole effort of the experts for the defence resolved itself into a guess. Professor Wilson had boasted that they had gottfip as much .as Professor Tonry yet they had only guessed at it.They used thirty grains of bismuth, aud got, as Professor Mallett estimated, not more* than the one-hundreth of a grain of arsenic; then how much arsenic was in the nine grains of bismuth administered to Maud L\ovd by Dr. Mott? Is it within the bounds of possibility that arsenic enough was in those nine grains of bismuth to have killed Maud Lloyd? It is a cruel slander upon Dr. Mott that he would keep and prescribe drugs that would carry death to his patieDts and patrons. He is fully vindicated here by the testimony of eminent chemists and Dr. Gorman. Cah the jury believe that the eight tenths of a grain of arsenic found by Prof. Tonry was contained in the nine grains of bismuth prescribed by Dr. Mott? The jury must be satisfied that the child died from arsenical poisoning. It is very rare in deed that a ease of poison can be proved, except by circumstantial evidence, for the crime can be committed in secret, and it leaves no traces of blood or weapons. If murder by poison can only be proved by circumstantial evidence, society would be at the mercy of the poisouer, who could practice his crimes almostrrifh imnnnitv.