PATHOLOGICAL TRANSUDATES, CYSTIC FLUIDS. 65 



moist precipitate in a mortar with water, adding some sodium 

 carbonate solution; if it does not dissolve, add a small quan- 

 tity of caustic soda solution. Filter, precipitate again with 

 acetic acid, and wash the precipitate with water. 



To distinguish mucin from nucleoalbumin we may use the 

 conduct of the precipitate on heating with hydrochloric acid 

 (see 1 below); mucin forms under these conditions a sub- 

 stance which reduces copper oxide in alkaline solution, while 

 nucleoalbumin does not ; nucleoalbumin contains phosphorus, 

 while mucin does not (see 2 below). To test for phosphorus 

 fuse the substance with soda and saltpeter, whereby the 

 phosphorus forms alkali phosphate. The presence of phos- 

 phoric acid in the fused mass is only to be regarded as proving 

 the presence of nucleoalbumin, when the precipitated proteid 

 is free from phosphates, especially calcium and magnesium 

 phosphates, and from the very widely distributed lecithin, 

 which contains phosphorus. 



The object of dissolving the precipitate in alkali solution, 

 filtering, and reprecipitating with acid is to remove the phos- 

 phates as completely as possible. 



1. Shake half of the moist precipitate of proteid with a 

 mixture (about 25 cc. or somewhat more) of three volumes of 

 water and one volume of hydrochloric acid, and heat in a 

 flask on the wire gauze to boiling, or heat part of the mixture 

 in a test-tube. Boil gently for about ten minutes, let cool, 

 make a portion alkaline with caustic soda solution without 

 filtering, then test with Fehling's solution, or add a small 

 quantity of copper sulphate solution, shake thoroughly, heat 

 to boiling, and cool the tube by placing it in water: in the 

 presence of mucin red cuprous oxide will be precipitated. 



2. Grind the other half of the precipitate in a mortar with 

 absolute alcohol, put the mixture into a flask, heat on the 

 water-bath to boiling, filter, and wash with some alcohol. 

 Press the moist precipitate between filter-paper, put it into 



