| Male. | Female. | ||||
| Specific gravity of defibrinated blood | 1·0600 | 1·0575 | |||
| Specific gravity of serum | 1·0280 | 1·0274 | |||
| Water | 779·00 | 791·00 | |||
| Fibrin | 2·20 | 2·20 | |||
| Fatty Matters | Serolin | 1·60: | 0·02 | 1·62: | 0·02 |
| Phosphorised fat | 0·49 | 0·46 | |||
| Cholesterin | 0·09 | 0·09 | |||
| Saponified fat | 1·00 | 1·05 | |||
| Albumen | 69·40 | 70·50 | |||
| Blood-corpuscles | 141·10 | 127·20 | |||
| Extractive matters | 6·80 | 7·40 | |||
| ——— | ——— | ||||
| 1000·10 | 1000·02 | ||||
| Salts | Sodium chloride | 3·10 | 3·90 | ||
| Other soluble salts | 2·50 | 2·90 | |||
| Earthy phosphates | 0·33 | 0·35 | |||
| Metallic iron | 0·57 | 0·54 | |||
| ——— | ——— | ||||
| 6·50 | 7·69 | ||||
The blood also contains, in solution, oxygen, nitrogen, carbonic acid, as well as a free alkaline carbonate, urea, and small traces of alcohol have also been detected in normal blood.
The following report of a commission composed of MM. Mialhe, Mayel, Lefort, and Cornil, appointed to devise the best method for the examination of blood stains, was published in 1873. The following translation of the report appeared in the ‘Chemical News’ of December 5th, 1873.
1st. When the stain is of recent date, or supposed to be so, the red corpuscles should be particularly examined, and every care taken to preserve them without change. The stains must not be washed with water, so that the hæmatin may not be altered. After insisting on the microscopic characters of the blood stains, isolated or compared with those of various animals, the commission enumerates with care the fluids which are destructive or preservative of blood-corpuscles. Among the first, water, and particularly hot water, acetic, gallic, hydrochloric, and sulphuric acids; and of alkalies, potash and soda, even in weak solution, and ether and chloroform, also many other reagents, so alter the blood-corpuscles as to cause them to entirely disappear. Alcohol, chromic and picric acids, and bichromate of potash, preserve the corpuscles, though they alter their form. The preservative fluids are those whose composition approaches nearest to serum, such as the iodised serum of Schultze, an excellent preparation made with amniotic fluid, to which are added a few drops of the tincture of iodine, so as to give it the colour of white wine; or, better, a fluid composed
thus; white of egg, 30 grams; distilled water, 270 grams; and chloride of sodium, 40 grams; or even a fluid containing 0·5 per cent. of chloride of sodium, or 5 or 6 per cent. of sulphate of sodium. If the stains be wetted and softened by these fluids, and then examined, white and red corpuscles and fibroid particles will be observed.
2nd. In more difficult cases, when the microscope, owing to the alterations which time has effected in the hæmatin, can give but vague information, examination by the spectroscope and chemical analysis enables us to arrive at precise results. The use of these means being less known, and also more delicate, requires special study.
1. Spectrum analysis. Colouring matters have the power of absorbing certain coloured rays of white light—the same always for the same substance. This is the principle upon which spectroscopic examination is based. If into any analysing tube filled with water a few drops of solution of hæmoglobin be introduced, till it has the colour of peach-blossoms, the luminous rays of the spectrum passing through this fluid present two bands of absorption, in the lines D and E of Frauenhofer, in the yellow and the green. The same fact would be observed if a few drops of blood were substituted for hæmoglobin in the analysis.
In a case of doubt the hæmoglobin of the blood could be reduced by adding to this latter a reducing body. Destroyed hæmoglobin has a different spectrum from oxygenated hæmoglobin, a single absorption band as large as the two former bands united, and a little to the left of Frauenhofer’s line D.
2. In blood in a state of decomposition, or which has been treated with acids or caustic alkalies, hæmoglobin is changed into a new substance; hæmatin is formed, which, combined with hydrochloric acid, gives definite crystals.
In order to obtain them we must proceed thus:—A small fragment of dried blood is placed on a glass slide; it is dissolved in a drop of water, and a minute portion of sea-salt added. It is covered with a thin slide, and pure acetic acid is made to pass between the two slides, and it is heated over a spirit-lamp to boiling-point; acetic acid is again added, and it is heated afresh; and this is repeated till the crystals are obtained.