324 APPENDIX 



VIII. METHODS WITH REGARD TO SOME SPECIAL 

 CHEMICAL CONSTITUENTS. 



IRON. 



The reactions mentioned below are given by inorganic salts 

 of iron, and probably by certain simple organic iron compounds. 



The tissue to be examined is best hardened in alcohol, but 

 various other hardening agents may be used. The sections after 

 treatment are washed with water, passed through alcohol, clove 

 oil, and mounted in balsam. 



a. Prussian blue method. A section is placed in a mixture 

 containing 1 p.c. hydrochloric acid and 1 p.c. potassic ferrocyanide 

 for 5 to 10 minutes. 



Another section is warmed to about 50 C. in the same fluid 

 for a few minutes (cp. p. 184, liver). 



The presence of iron will be shown by blue particles, or by a 

 diffuse blue stain. 



b. Hsematoxylin method. A section is placed for a few 

 minutes in a *5 p.c. solution of hsematoxylin in distilled water 

 (a brownish-yellow solution). The parts containing inorganic 

 iron salts stain blue-black or blue- violet ; elsewhere the colour 

 is reddish brown, and this tends to hide the iron stain; it is 

 removed by placing the sections for to 1 hour in a mixture 

 of equal parts of absolute alcohol and ether. According to 

 Macallum inorganic iron salts only are stained by this method. 



Ammonium sulphide in dilute glycerine is also used, and the 

 sections mounted in dilute glycerine, but methods a and b are prefer- 

 able. 



The more complex iron compounds do not give the iron 

 reactions ; in order to detect the presence of these, the compound 

 must be split up. This may be done by treating sections with 

 a 95 p.c. alcohol containing 4 p.c. sulphuric acid in the warm, and 

 taking a section from time to time (1 to 24 hours), washing the 



