22 PRACTICAL MICROSCOPY/. 



watched carefully and when, on cutting through a piece, the fluid is 

 found to have stained the blocks completely, taking from two to 

 three, or even four weeks, remove to a large jar of clear water and 

 wash, changing the water frequently for twenty-four hours. The 

 washing having removed the chromic acid, the tissue is further hard- 

 ened in Alcohol A, B, 0. 



The special applications of this method, as well as of those which 

 will follow, are indicated in Part Third. 



MULLER'S FLUID (MODIFIED).* 



Bichromate of potash, .... 25 grammes. 

 Sulphate of copper, ... . 5 " 



Water, 1,000 c.c. M. 



This may be employed in precisely the same manner as the dilute 

 chromic-acid solution. 



DECALCIFYING PROCESS. 



6f c Chromic acid solution, . . ' .. 9 parts. 



Citric acid, C. P., . . . . . 1 part. 



Water, . .90 parts. 



The earthy salts may be removed from teeth and small pieces of bone 

 with a liberal supply of the above in about twenty days. A frequent 

 change of the solution will greatly facilitate the process; and an occa- 

 sional addition of a few drops of the nitric acid may be made, with very 

 dense bone. After the removal of the lime salts, the pieces may be 

 preserved in alcohol until such time as sections are needed, when they 

 may be cut with the microtome without injury to the knife. 



DISSOCIATING PROCESS (W. STIRLING). 



Artificial Gaslric Fluid. 



Pepsin, 1 gramme. 



Hydrochloric acid, . . . . 1 c.c. 



Water, . 500 c.c. M. 



This process depends for its value upon the fact that certain con- 

 nective tissues are more rapidly dissolved by the fluid than others. 



BAYBERRY TALLOW, HARDENING OR INFILTRATING PROCESS. 



Some three years since, I devised a method of infiltrating tissues 

 with bayberry tallow. Tissues like lung, etc., which are delicately 



* The original Muller's fluid consists of the above (minus the copper salt) 

 with an addition of 12.5 grammes of sulphate of soda. 



