172 CHAPTER XII. 



222. RANVIER'S Picro-carmine, Original Formula (Traite, p. 100). 

 To a saturated solution of picric acid add carmine (dissolved in ammonia) to 

 saturation. Evaporate down to one fifth the original volume in a drying 

 oven ; and separate by filtration the precipitate, pour in carmine, that forms 

 in the liquid when cool. Evaporate the mother-liquid to dryness, and you 

 will obtain the picro-carmine in the form of a crystalline powder of the 

 colour of red ochre. It ought to dissolve completely in distilled water ; a 

 1 per cent, solution is best for use. 



For slow staining, dilute solutions may advantageously have 1 or 2 per- 

 cent, of chloral hydrate added to them. 



Overstains maybe washed out with hydrochloric acid, say O'o per cent., in 

 water, alcohol, or glycerin. 



Preparations should be mounted in balsam, or if in glycerin, this should 

 be acidulated with 1 per cent, of acetic acid, or better, formic acid. 



223. RANVIER'S Newer Formula does not give a more constant pro- 

 duct (see previous editions). 



224. MATER'S Pier o -magnesia Carmine (Zeit. f. wiss. Mile., xiv, 

 1897, p. 25) is relatively constant and innocuous to tissues. It consists of 

 1 vol. of the stock solution of magnesia-carmine ( 220), and 10 vols. of a 

 0'6 per cent, solution of picrate of magnesia, or of equal parts of the weak 

 solution and the picrate solution. The picrate may he obtained from 

 GRUBLER & HOLLBORN, or the solution may be made by heating 0'25 

 grins, of carbonate of magnesia in 200 c.c. of O'o per cent, solution of picric 

 acid, allowing to settle and filtering. 



225. Other Formulae for Picro-carmine. I have tried most of 

 them, and found no real advantage in any of them (see previous editions). 



226. Other Aqueous Carmines (Acid and Alkaline). For all 

 of them see previous editions. 



B. ALCOHOLIC CARMINE STAINS. 



227. Alcoholic Borax-carmine (GRENACHER, Arch. f. Mik. 

 Ainit., xvi, 1879, p. 466, / seq.). Make a concentrated 

 solution of carmine in borax solution (2 to 3 percent, carmine 

 to 4 per cent, borax) by boiling- for half an hour or more ; 

 dilute it with about an equal volume of 70 per cent, alcohol, 

 allow it to stand some time (twenty-four hours MAYER), 

 and filter. Or the mixture of carmine and borax solution is 

 (il/on-i'd to nt(i)i-d fur tiro or tlira' dtnjs and occasionally stirred ; 

 the greater part of the carmine will dissolve. To the solution 

 is added an equal bulk of 70 per cent, alcohol ; the mixture 



