THE CARBOHYDRATES. 19 



(c.) Filter, and to the nitrate add ammonium oxalate 

 a white precipitate of oxalate of lime, showing that there is 

 lime present, but not as a phosphate. 



(d.) To the solution of mineral matters 14, A. (a.) add 

 acetate of soda until there is free acetic acid present, re- 

 cognised by the smell ; then add ammonium oxalate = a 

 copious white precipitate of lime salts. 



Exercises on the Foregoing. The solution may contain one 

 or more proteids or carbohydrates. 



A. Proteids. 



(1.) Note the colour, odour, and transparency of the solution. 



(2.) Test its reaction. Neutralise by dilute sodic carbonate 

 or hydrochloric acid, if necessary. If the precipitate gives the 

 xanthoproteic reaction, it is acid or alkali-albumin. If not, it is 

 earthy phosphates. 



(3.) Do the xanthoproteic reaction, which shows the presence 

 of a proteid. 



(4.) Boil. If there is coagulation it is either egg-albumin, 

 serum-albumin, or globulin. 



(a.) Test if the solution is precipitated by crystals of mag- 

 nesic sulphate = globulin. Filter. 



(6.) Test the nitrate of (a.) by acidulation and heat for 

 albumin. Confirm by other tests. 



(c.) Test the filtrate of (6.) for peptones. 

 (5.) Test for gelatin. 



B. Carbohydrates. 



(1 .) Remove any proteids present, except peptones, by acidi- 

 fication and boiling, and use this solution for testing. 



(2.) Add iodine after acidulation if necessary, a blue colour = 

 starch ; a port- wine colour = dextrin or glycogen. Confirm by 

 other tests. 



