If there be reason to suspect the presence of both sulphuric and oxalic acids, the distillation is discontinued after a short time. The two acids are dissolved by shaking the moderately concentrated fluid remaining in the retort with ether, and, upon evaporating the solution, will be obtained in a state suitable for examination. Oxalic acid is then detected by means of sulphate of lime; sulphuric by means of oxalate of baryta.
The above examinations would fail to effect the detection of phosphorus, and it is necessary to examine a separate portion of the original substance for this body.
[IV.
MISCELLANEOUS EXAMINATIONS.]
DETERMINATION OF THE NATURE AND COLOR OF THE HAIR AND BEARD.
A criminal, in order to conceal his identity, may change the color of the hair and beard by artificial means; either to a darker shade, in case they were naturally of a light color, or, to a lighter hue, if they were originally dark, and the chemical expert may be called upon to detect this artificial coloration, and restore the original color of the hair.
It may also happen, that portions of hair still adhere to the clots of blood sometimes found on an instrument which has been employed in the commission of a crime, and consequently the question may arise as to the nature of the hair, whether it be human or animal.
DETERMINATION OF THE COLOR OF THE HAIR AND BEARD.
The mode of examination necessary when the hair has been blackened is different from that used when it has been decolorized.
The hair has been blackened.
As various methods of dyeing hair black are in use, the means of restoring the original color differ. The following are the methods most usually employed in dyeing: