The Microscope. 115 



put on, but each should be allowed to dry before adding another. 

 (Gage.) 



Another method which is taught in Heidelberg, (we do not 

 remember the originator's name.) which yields beautiful results, 

 is as follows : Allow fi-esh blood to fall drop by drop into a solution 

 of osmic acid (2 per cent, acid solution, one part ; 1 per cent, solu- 

 tion sodium chloride, two parts ; distilled water, one part.) The 

 solution should be constantly stirred while the blood is dropping. 

 Allow the blood and acid to stand over night, and then wash the acid 

 away with distilled water. Add alcohol, then clove oil, in which the 

 blood may be kept indefinitely. Before the alcohol is added the 

 nucleus of the corpuscle may be stained in aliun-carmine, the blood 

 aftei-wards being washed ; or the whole corpuscle may be stained in 

 analine blue. We have slides of salamander and dog's blood pre- 

 l^ared in this way some years ago, which are as beautiful to-day as 

 when first finished. 



Gibbes' method of staining blood is essentially the same as that 

 recommended by Gage. First spread the blood on the cover-glass 

 and expose to fumes or immerse in osmic acid. Then wash with 

 distilled water and cover the blood with the staining fluid, which 

 should be allowed to remain for a few minutes. Gentian violet or 

 rosanilin acetate are recommended as colors. When stained, the 

 blood should be washed in water and then in methylated spirit until 

 no more color is given off. Allow cover to dry and then mount in 

 Canada balsam. 



To Sharpen Razors. — The simplest method of sharpening a 

 razor is to put it for half an hour in water, to which has been added 

 one-twentieth of its weight of (HCl) hydrochloric acid water (which 

 is muriatic acid), or sulphuric acid, then lightly wipe and after a few 

 hours set it on a hone. The acid here supplies the place of a whet- 

 stone, by corroding the whole siu'face uniformly, so that nothing 

 further than a good polish is necessary. The process never injures 

 good blades, while badly hardened ones are fi'equently improved by 

 it. — Scientific Enquirer. 



Preparing Horse-Hoofs. — In Dr. C. Norner's investigations, 

 (Arch, filr Mikr. Anat. xxviii, 1886) directed chiefly towards the dis- 

 covery of nerve-fibres, the hard corneous layers were first removed 

 from the hoof, and then small pieces of the softer tissues were cut 

 out and placed in osmic acid and gold chloride. Pieces of tissues 

 were placed in osmic acid (1 : 100) for 24 to 48 hours, they were then 



