Practical Histology And Pathology

n be hardened in spirit alone if they are placed in dilute spirit at first, so that the elements of which they are composed are not shrunk. This process is also used after hardening by any of the others. Dilute spirit is made by adding i part of water to 2 parts of methylated spirit. The material to be hardened should not be left in this mixture more than from 24 to 48 hours. It is then transferred to pure methylated spirit. 4. Bichromate of Potash. Make a 2 per cent. solution and keep it on hand, as it is very useful for many tissues that require slow hardening. A solution can be made much more quickly with warm water than cold. This solution is also very useful to place portions of morbid material in, on their removal from the body in the post-mortem room, they can afterwards be transferred to the chromic acid mixture for more rapid hardening. This solution takes from three to seven weeks to harden, according to the size of the specimen, and the frequency with which the solution is changed. 5. Bichromate of Ammonia. A 2 per cent. solution is used in precisely the same manner as the former, and is applicable to the same tissues. 6. Cliromate of Ammonia. Make a 5 per cent. solution, that is i oz. of the salt to 20 oz. of water, or 5 grammes to 100 c.c., and filter. Keep it in a stoppered bottle. When this hardening agent is used for fresh tissue, such as mesentery, a small quantity is placed in a glass vessel and the tissue immersed in it for 24 ...