388 APPENDIX. 



alcohol, or embed and cut in paraffin. Get rid of the paraffin by means of 

 turpentine, and treat both the paraffin and alcohol sections with chloroform 

 in which iodine is dissolveil, and mount in chloroform balsam containing some 

 iodine. The brown stain in the liver cells indicates glycogen, which is 

 deposited chiefly in the cells around the hepatic vein [DeUpine). 



Iron. — (a.) The tissue — liver ot young animal, or spleen— must be hardened 

 in alcohol. The sections are transferred to a freshly -prepared solution of 

 potassium ferrocyanide acidulated with hydrochloric acid. The granules of 

 iron become blue {Tizzoni). 



{b.) Harden the liver in 65 p.c. alcohol, then in 90 p.c. alcohol to which a 

 few drops of sulphuretted hydrogen are added. After twenty-four hours the 

 iron granules become green {ZahsJci). 



Phosphorus. — Place sections of the fresh organ for half an hour in a strong 

 solution of ammonium molybdate, and then transfer them to a 20 p.c. 

 solution of pyrogallic acid dissolved in ether. After a few minutes pass 

 them through spirit and clove oil, and mount in Canada balsam. A com- 

 pound containing phosphorus is stained yellow or brown, and such compounds 

 are usually found in the nuclei. It is stated that by this method nucleo- 

 albumin may be distinguished from mucin {LUienfeld and MorUi). 



KJELDAHL'S METHOD OF ESTIMATING NITROGEN. 



1. Destruction of Organic Matter. — Place in a boiling flask ot ICX5 cc. 

 capacity o. i-i gramme of the powdered dry substance. To destroy the organic 

 matter add 10-20 cc. of the following mixture : 200 cc. pure oil of vitriol, 50 

 cc. Nordhausen oil of vitriol, phosphoric acid in sticks, 2 grammes, all free 

 from ammonia. Heat on a wire gauze with a Bunsen-burner, but keep the 

 temperature below boiling. To hasten the destruction a little potassium 

 permanganate may be added. Heat for 1-2 hours until the fluid becomes 

 clear and greenish. 



2. Neutralisation. — Cool the flask, add a little water, and wash the contents, 

 with as little water as possible, into a large flask of 700 cc. capacity. 

 Neutralise with pure caustic soda or potash (S.G. 1.13). Add a little 

 metallic zinc to prevent bumping during the subsequent distillation. 



3. Distillation. — Rapidly close the flask with a perforated caoutchouc stopper 

 through which passes a tube with two i inch bulbs blown upon it. The bulbs are 

 to collect and prevent the passage of soda spray. The tube above the bulbs 

 passes through a condenser, and the delivery tube end of the condenser tube 

 passes into a flask containing a measured excess of standard acid (HCl). 

 Distil the mixture about an hour in the flask, and the ammonia passes over 

 into the acid. 



