58 MICRO-ORGANISMS. 



A freshly made 2 p. c. solution is 50 p. c. stronger in colour ; but ifc 

 crystallizes out in cold weather. Owing to the influence of some soluble 

 impurity, a 10 p. c. solution gives a weaker colour than a 2 p. c. 



(c) Koch's Methylene Blue Solution. Saturated Alco- 

 holic Solution of Methylene Blue, 1 cc. ; 10 p. c. solution of 

 Caustic Potash, 0-2 cc. ; Distilled Water, 200 cc. 



This formula is taken from Koch's paper, "Die Aetiologie der Tuber - 

 culose in Berliner Klinische Wochenschrif t, " 1882, No. 15, p. 221. In 

 most English text-books, the quantity of alkali is increased ten times, 

 owing to the omission of a decimal point in the translation from which 

 these are copied. 



(d) Lb'ffler's Solution. Concentrated Alcoholic Solution 

 of Methylene Blue, 30 cc. ; Solution of Caustic Potash (1 in 

 10,000), 100 cc. 



(e) Kuhne's Carbolic Methylene Blue. Methylene 

 Blue, 1-5 grms. ; Absolute Alcohol, 10 cc. Eub in a mortar, 

 and add 100 cc. of a 5 p. c. Aqueous Solution of Carbolic Acid. 



(/) Xiihne's Aniline Oil Solution. Eub up in a mortar 

 as much Methylene Blue as will go upon the point of a knife, 

 with 10 cc. of Aniline, and pour the whole unfiltered into a 

 bottle ; after a time the undissolved pigment will settle at the 

 bottom. 



(in.) GENTIAN VIOLET. 



(a) Concentrated Alcoholic Solution. Gentian Violet, 

 25 grms. ; Absolute Alcohol, 100 cc. 



(5) Aqueous Solution. Gentian Yiolet, 1 grm. ; Eectified 

 Spirit, 20 cc. ; Distilled Water, 80 cc. 



(c) *Gentian-Violet Aniline- Water. Aniline Water, 100 

 cc. ; Concentrated Alcoholic Solution of Gentian Yiolet, 1 1 

 cc. ; Absolute Alcohol, 10 cc. 



(iv.) METHYL VIOLET. 



(a) Concentrated Alcoholic Solution. Methyl Yiolet, 

 25 grms.; Absolute Alcohol, 100 cc. 



* " Erhlich-Weigert-Koch " formula. 



