CORROSIVE SUBLIMATE 357 



the sublimate-acetic mixture kill and penetrate more 

 rapidly if used hot, at a temperature of 70 or 80 C. 

 Many forms can be killed and fixed in an extended 

 condition by plunging them rapidly from a dish of sea 

 water in which they are well expanded into a vessel 

 containing hot corrosive sublimate solution. 



The time during which objects must remain in corro- 

 sive sublimate solutions varies very much, especially 

 with their size. Small delicate organisms will be suffi- 

 ciently fixed in ten to fifteen minutes. Larger organisms 

 and pieces of compact tissue may remain from one to 

 twenty-four hours with advantage. 



After removal from the sublimate solution or subli- 

 mate-acetic mixture, the objects are rinsed in fresh 

 water, and then transferred to 70 per cent, alcohol, to 

 which a few drops of tincture of iodine * are added. A 

 considerable volume of the alcohol should be used, and 

 enough iodine to make it of " a good port wine colour." 

 The colour is gradually destroyed by the corrosive 

 sublimate. When the alcohol has lost all the colour 

 it should be changed, and fresh tincture of iodine 

 added. This process should be repeated until the 

 iodine colour remains for twelve or twenty-four hours, 

 when the object is removed to fresh 70 per cent, 

 alcohol, without the addition of iodine, in which it 

 may be left. 



Corrosive sublimate is more soluble in alcohol than 

 in water, and a saturated solution in 70 per cent, 

 alcohol is sometimes used for fixing with good results. 

 It is also more soluble in sea water (or common salt 

 solution) than in distilled water, and the sea water 

 solution is sometimes recommended. In both these 

 cases the subsequent treatment of the specimens is 



* Tincture of iodine is made by dissolving iodine in strong 

 alcohol. 



