ZOOLOGY AND BOTANY3 MICROSCOPY, ETC. 677 



safranin powder. The mixture is then heated to 60°-80° and filtered. 

 Thus made the fluid is clear and deep red, and it will keep for one or 

 two months. 



Metanil-yellow.* — This is a yellow powder with sp. gr. 1-3102, 

 soluble in water, 12 parts aq. destil. at 16° C. dissolving 0-031 grra. 

 The watery solution is orange coloured and neutral on reaction. On 

 evaporation, crystals are formed which belong to the rhombic system. 

 Dr. H. Griesbach says that, for microscopical investigation it may 

 be used for staining tissues, to which it imparts usually a yellow colour, 

 the tone of which may vary from a bright to a dark hue. It may also 

 be used as a double stain in conjunction with other dyes, such as Congo 

 red, methyl-violet, acid fuchsin, so that a double or triple staining, 

 according to the combination, is effected. 



Simple Method for clearing Methylen Iodide, f — Herr E. Brauns 

 found quite accidentally a method for clearing methylen iodide which 

 has become brown. Some brownish methylen iodide happened to 

 become frozen, only a small quantity, dark brown in colour, remaining 

 fluid. When the latter was poured off, and the methylen iodide melted, 

 the methylen iodide was found to be of a pale yellow colour and of 

 excellent quality. At 15° C. the sp. gr. = 3 • 330. 



As methylen iodide solidifies at 5° C, it is only necessary to expose 

 it to comparatively slight cold to clarify it in the best and simplest 

 manner. 



Carmine Injections. | — Trouble with carmine gelatin fluids when 

 used for micro-injections, arises, says Dr. W. C. Borden, in two ways, 

 either from an excess or deficiency in the amount of acid used to pre- 

 cipitate the carmine. In the first case the carmine precipitates in a 

 too coarsely granular form, in the second, all the ammonia not being 

 neutralized, the ammoniacal solution of carmine will diffuse through the 

 walls of the blood-vessels. The difficulty is obviated by determining 

 beforehand the exact amount of acid which it takes to neutralize a given 

 quantity of ammonia — that quantity which is to be used in the fluid made. 

 To this end take a drachm of aq. ammonise, and add gradually, with 

 constant stirring, acetic acid, testing with blue litmus paper. The instant 

 the paper changes to red stop adding the acid and note the amount which 

 has been used. Suppose that it is If dr., then the proportion of acetic 

 acid will be 11 to 6, and if the amount of ammonia used be 4 dr., 

 then the amount of acid needed will be 7^ dr. In this way the proper 

 amount of acetic acid to ammonia may be found in any formula. The 

 following formula is recommended as being the best of the gelatin- 

 carmine warm flowing masses. 



Carmine solution : — Carmine No. 40, 4 dr. ; aq. ammoniee fort., 4 dr. ; 

 water, 6 oz. Grind the carmine in a mortar, gradually adding the water, 

 then add the ammonia, and heat gently until the carmine is dissolved. 



Gelatin solution : — Gelatin, 1-^ oz. ; water, 7f oz. Soak the gelatin 

 in the water until soft, and then dissolve by heating. Take 5 oz. of the 

 gelatin solution and add to it the solution of carmine. Add to the re- 

 mainder of the gelatin solution sufficient acetic acid as found by previous 

 trial to neutralize 4 dr. of ammonia contained in the carmine solution. 



* Zeitschr. f. Wiss. Mikr., iv, (1887) pp. 439-62 (4 figs.), 

 t Neues Jahrb. f. Mineral., Geol. u. PalseontoL, 1888 (i.) pp. 213-4. 

 t Amer. Mon. Micr. Journ., ix. (1888) pp. 39-41 (1 fig.). 

 1888. 3 A 



