OTHER GOLD METHODS. 149 



part HC1 to 1000 parts of 60 per cent, alcohol, then for a few 

 minutes into absolute alcohol, and thence into clove oil, for 

 mounting in balsam. 



FLECHSIG (Die Leitungsbahnen im Gehirn, 1876 ; Arch. f. 

 Anat. u. Phys., 1884, p. 453) reduces in a 10 per cent, solution 

 of caustic soda. 



NESTEROFFSKY treats impregated preparations with a drop 

 of sulphydrate of ammonium, and finishes the reduction in 

 glycerin (quoted from Gierke's Farberei z. mik. Ziueckeri) . 



BOHM reduces in PRITCHARD'S solution. 



PRITCHARD'S SOLUTION consists of amyl alcohol, 1 per cent. ; 

 formic acid, 1 per cent. ; and water, 98 per cent. 



MANFRED: treats fresh tissues as follows (Arch, per le Sci. 

 med., v, No. 15) : Gold chloride, 1 per cent., half an hour; 

 oxalic acid, 0*5 per cent. ; they are then warmed in a water- 

 bath to 36, allowed to cool, and examined. Mount in gly- 

 cerin. Sunny weather is necessary. 



He treats tissues previously hardened in 2 per cent, solu- 

 tion of bichromate of potash, as follows (ibid.) . They are put 

 for half an hour into solution of arsenic acid, or into 1 per 

 cent, acetic acid. They are then put into 1 per cent, gold 

 chloride for half an hour, washed in water, and reduced in 

 sunlight in 1 per cent, arsenic acid solution, which is changed 

 for fresh as fast as it becomes brown. Mount in glycerin. 

 Sunny weather is necessary. 



BOCCARDI (Lavori Istit. Fisiol. Napoli, 1886, i, p. 27; Journ. 

 Roy. Mic. Soc., 1888, p. 155) recommends oxalic acid of 0*1 

 per cent, or of 0*25 to 0*3 per cent., or a mixture of 5 c.c. pure 

 formic acid, 1 c.c. of 1 per cent, oxalic acid, and 25 c.c. of 

 water. Objects should remain in this fluid in the dark not 

 longer than two to four hours. 



KOLOSSOW (Zeit.f.wiss.Mik., v, 1, 1888, p. 52) impregnates 

 for two or three hours in a 1 per cent, solution of gold chloride 

 acidulated with 1 per cent, of HC1, and reduces for two or 

 three days in the dark in a O'Ol per cent, to 0'02 per cent, 

 solution of chromic acid. 



UNDERWOOD (Journ. Brit. Dental Ass., xi, 1890, p. 696 ; 

 Journ. Roy. Mic. Soc., 1890, p: 815) gives the following : 

 Wash sections in bicarbonate of soda (strength not given) ; 

 treat them for half an hour to an hour with 1 per cent, solu- 

 tion of chloride of gold, neutralised if acid by bicarbonate of 



