240 THE MICHOSCOPE 



funnel, pack it loosely, and then percolate enough water through 

 it until the liquid is but slightly coloured. Allow the logwood to 

 drain thoroughly, remove from the percolator, and spread out on 

 a paper to dry. Dissolve the alum in 8 fluid ounces of water, 

 moisten the dry logwood with a sufficient quantity of fluid, and 

 pack again in the funnel rather tightly, pour on the remainder of 

 the alum solution. When the liquid percolates through and com- 

 mences to drop, close the aperture with a well-fitting cork, and 

 allow the logwood to macerate for forty-eight hours. Then remove 

 the cork, and allow the liquid to drain off; pour sufficient water 

 upon the drug, and percolate through 12 fluid ounces altogether. 

 Mix this with the glycerine, filter, and place in a stoppered bottle. 

 A few drachms of alcohol may be added to increase its preserva- 

 tive qualities. It yields good results when used undiluted, as a 

 quick stain ; but we prefer placing the tissues in a weak solution 

 (lo drops to 2 fluid drachms), with warm, distilled water, for 

 about twelve hours. Its advantages are : its permanency, beauti- 

 ful violet colour, clear and sharp definition, and can be used with 

 the very highest powers. 



Gibbes' Logwood. — Extract of haematoxylin, 6 grms. ; albu- 

 men, 18 grms. Mix thoroughly; while mixing, add 28 cc. of 

 distilled water. Filter. Add to the filtrate i drachm of rectified 

 spirits of wine ; let it be kept in a stoppered bottle for a week 

 before using. What remains on the filter can be mixed with 

 14 cc. of distilled water, and left soaking in it for an hour or so; 

 then filter, and add to the filtrate J drachm of rectified spirit. 

 The second solution is as strong as the first. The alum used 

 must be potash without ammonia, and the extract of haematoxylin 

 must be English. 



Klein's Logwood Stain.— Mix 5 grms. of the officinal extract 

 of haematoxylin with 75 grms. of alum in a mortar, and pulverise 

 carefully. To this add gradually 25 cc. of distilled water, and 

 filter. To the residue add 15 cc. of distilled water, and again 

 mix in a mortar and filter. To this filtrate add 2 cc. of alcohol. 

 Now mix the two filtrates, and keep in a glass-stoppered bottle. 

 If the liquid ever becomes mouldy, filter again. Care must be 

 taken to prevent any acid from intermingling with the fluid. Acids 



