360 THE ANALYST. TOXICOLOGICAL ANALYSIS. The Forensic Value of ( ( Florence's Crystals.” N. Bocarius. ( VierteZjahr- schr. gericht. Med. u. ofentb. Sanitatsw. , 1901, xxi., 255-266; through Zeit. f.iir Untersuch. der Nahr. und Genuussrnittel, 1902, v., 942,943.)-Florence’s crystals (see ANALYST, xxiii., 320) are not onlyobtained with human seminal fluid, but also with that of animals as well as with other animal and vegetable substances, such as extracts from the liver, the blood of common insects, caterpillars, etc. The crystals are always obtained even ’from the smallest trace of human semen, whether it be wet or dry, fresh or decom- posed, except when the semen is coloured emerald-green or orange by micro-organisms. Animal seminal fluid and bodies not of a spermatic nature react more feebly with the iodine (Florence’s) solution than does human semen.The crystals may be obtained with various iodine solutions, but the reagent must contain excess of iodine. The age of the seminal traces does not influence the reacbion, nor does a high temperature or decomposition, but the presence of large quantities of blood, and other animal fluids, interferes with the formation of the crystals; an excess of liquid-water or reagent-as well as an excess of potassium iodide in the latter, should be avoided. The form of the crystals is altered accordingTHE ANALYST. 361 to the reagent used, and by other causes. The actual substance which forms the crystals in the presence of iodine exists not only in seminal fluids, but also in many organic bodies. Florence's reagent is, therefore, only a selective test.W. P. 8. The Nature of the Substance which causes the Formation of " Florence's Crystals.'' (Zeit. physiok Che~n., 1902, xxxiv., 339-346 ; through Zeit. fiir Untersuch. der Nahr. and Genussmittel, 1902, v., 943.)-To ascertain the nature of these crystals the author carried out a number of experiments with the seminal fluids of men and horses, the livers of oxen, and human brains and livers. These were first treated with 2 per cent. formaldehyde solution, and by acting on the extracts of the various objects with a solution of iodine in sodium iodide large quantities of crystals were obtained. The latter keep well if allowed to stand in the iodine solution. After decomposing the crystals with silver hydroxide, the products were treated with alcohol, and converted into platinum chloride salts. On analysis the latter were found to the following percentages of platinum : human semen, 31.65 ; animal semen, 31-51; human liver, 31.82; OX liver, 31-53; and human brain, 31.61.The average of these figures is 31.62 per cent., whilst choline-platinum chloride gives 31.64, and semen-platinum chloride 38.21 per cent. of platinum. The author comes to the conclusion that choline must be considered as the substance which forms the N. Bocarius. crystals with the iodine solution. (See ANALYST, xxiii., 320.) w. P. s. Determination of Mercury in Toxicological Work, C. Pierpaoli. (Boll. Chim. Farm, 1902, xli., 561 ; through Chem. Zeit. Rep, 1902, 265.)-According to the author, the partial loss of mercury which occurs when animal substances have been destroyed by the Fresenius-Babo process is due to the following causes : In the precipitate produced by sulphuretted hydrogen the mercuric sulphide is accompanied by organic matter containing chlorine, from which it cannot be freed by washing with water ; on the contrary, by excessive washing part of the sulphide passes into the colloidal modification, and is therefore lost. When the dry impure sulphide comes to be treated with nitric, and afterwards with sulphuric, acid, in order to complete the destruction of organic matter, part of the mercury is converted into chloride by the chlorine present, and volatilized when the sulphuric acid is warmed. AS a matter of fact, Pierpaoli has found that if mercuric chloride is heated with sulphuric acid to a temperature not exceeding 170" C. the salt is not decomposed, but volatilizes unchanged. F. H. L.