Aug. i6, 191S Phosphorus Metabolism of Lambs 461 



The bag was lined with oilcloth in order to prevent loss of moisture and 

 solid material. The feces were taken from these bags at 2 p. m. daily. 

 Under the wire grating of each cage there was a galvanized-iron tray, 

 which acted as a collecting funnel for the urine. The lambs were fed 

 twice each day, at 7 a. m. and at 4 p. m. The concentrates were fed 

 about 20 minutes before the alfalfa hay, and the grain orts were collected 

 just before the hay was fed. The hay orts of the previous feeding were 

 collected before each new feeding. The metabolism test proper extended 

 from December 23 to January 3, inclusive. 



METHODS OF ANALYSIS 



The methods of analysis used in this experiment were essentially the 

 same as the official methods of analysis of the Association of Official 

 Agricultural Chemists * for all determinations except for the different 

 forms of phosphorus. 



The methods used in determining the different forms of phosphorus in 

 the feeds and feces were as follows : 



(a) Method op making a 0.2 per cent hydrochloric- acid extract. — A sample of 

 suitable size (about 100 gm. of feces or 50 gm. of feed) was divided about equally 

 between two 500 c. c. centrifuge bottles. A little powdered thymol and 300 c. c. of 

 a 0.2 per cent hydrochloric-acid solution were added to each bottle. The bottles were 

 wired spoke-wise to a bicycle wheel, which was revolved at the rate of about 38 revo- 

 lutions per minute, and were shaken in this manner for from 12 to 14 hours. 



The bottles were then opened, the sides of each washed from a pipette with 25 c. c. 

 of the acid solution, and then they were placed in the centrifuge, running at the rate 

 of about 1,700 revolutions per minute, for 10 minutes. The clear solution in each 

 bottle was carefully decanted into a 3-liter measuring flask. Then 100 c. c. of the 0.2 

 per cent acid solution were added to each bottle. The bottles were shaken till the 

 contents were homogeneous and the sides washed again with 25 c. c. of the solution. 

 This process of extraction was repeated nine times. Generally a tenth extraction 

 was made and tested qualitatively. The solution in the measuring flask was then 

 made up to the mark with the 0.2 per cent hydrochloric-acid solution and thor- 

 oughly mixed. If the solution in the flask was quite thick with sediment, it was 

 allowed to settle and then the liqiiid was decanted through a lo-inch qualitative falter. 

 The filtering was repeated till the filtrate was perfectly clear. 



(6) Total acid-solublE phosphorus determination. — Triplicate samples of 

 100 c. c. each of the clear 0.2 per cent hydrochloric-acid extract were evaporated to 

 dryness in weighed, ignited 3-inch porcelain dishes, and ashed. The total phosphorus 

 of this ash was determined in the usual manner. 



(c) AciD-iNSOLUBLE PHOSPHORUS was determined by subtracting the total acid- 

 soluble phosphorus from the total phosphorus of the feeds or feces. 



{d) Inorganic acid-soluble phosphorus determination.— Triplicate samples 

 of 150 c. c. of the acid extract were each treated with 25 c. c. of magnesia mixture. 

 This magnesia mixture was added slowly, drop by drop, while the solution was being 

 stirred. After the solutions had stood for 15 minutes, 20 c. c. of ammonia (sp. gr. 

 C.90) were added to each beaker and the sohitions allowed to stand for 12 hours. At 

 the end of this time the solutions were filtered through double 11 cm. filters and the 



• Wiley, H. W., et al. OfBcial and provisional methods of analysis. Association of Official Agricultural 

 Chemists. U. S. Dcpt. Agr. Bur. Cheni. Bui. 107 (rev.). 272 P-, n fig- 1908. 

 96502°— 15 7 



