300 PROCEEDINGS OF THE ACADEMY OF [1883. 



tion. As soon as the liquid percolates through and commences to 

 drop from the end of the percolator, close the apeilure with a 

 tightly fitting cork, and allow the drug to macerate for forty-eight 

 hours. Remove the cork at the expiration of that time, allow the 

 liquid to drain off, and then pour sufficient water upon the drug 

 to percolate through twelve fluid-ounces altogether. Mix this with 

 the glycerine, filter and place in a close-stopped bottle. 



In this process nearly all the tannin is removed by percolating 

 the drug with cold water, a menstruum in which the coloring 

 principle is not very soluble, and the subsequent maceration and 

 percolation witli the alum solution removes the logwood lake in a 

 state of comparative purit3% The glycerine is added simpl}' for 

 its preservative qualities, and this ma}' be still increased by the 

 addition of a few drachms of alcohol to the solution. 



The heraatin staining fluid thus prepared is a clear, heavy fluid 

 of a deep purplish red color. It will keep its color for a length of 

 time, and deposits no sediment. The sample exhibited to the 

 meeting this evening has been on my working table for nearly a 

 year, frequently' exposed to a strong light and open to the air, 

 and, as you may see, it is as 3'et unchanged. As a staining fluid, 

 used either strong or diluted, I consider it far superior to an}^ 

 other stain I know of. Permanent and beautiful in its color, 

 which is of a delicate violet hue, clear and sharp in its definition 

 of the different tissues under examination, it will bear use with 

 the very highest powers of the microscope, and, I hope, enable 

 observers to distinguish minute differences of tissue which have 

 hitherto escaped notice. 



A few words in conclusion as regards the method of using this 

 fluid. It yields good results, when used undiluted, as a quick 

 stain ; but the most excellent results, to my mind, are obtained by 

 placing the tissues in a weak solution (ten drops to two fluid- 

 drachms), with warm distilled water, for about twelve hours. This 

 method leaves nothing to l)e desired, and produces results of 

 surpassing delicacy and beauty. I had intended, in conclusion, 

 to refer to the beautiful double-staining produced by this agent 

 in connection with a new preparation of indigo-sulphuric acid, 

 and have several specimens on exhibition this evening ; but I 

 thiuk it will be best to devote a separate paper to the consid- 

 eration of this suV)jeet, which I trust to be able to present at a 

 future meetino- of this Section. 



