1895.] PUBLIC DOCUMENT — No. 33. 319 



Comments on Table II. 



The first two columns show the sources of nitrogen and 

 the quantity apj)lied to each pot. Tlie third column shows 

 the total average nitrogen found in the dry matter pro- 

 duced by each pot. Where no nitrogen was applied, the 

 soil yielded of itself .0945 gram, and the excess over 

 this amount obtained in the other series represents the 

 amount that the plants succeeded in getting from the 

 nitrogen applied. The next column shows that for every 

 100 parts of nitrogen applied in the form of nitrate of soda 

 70 parts were obtained in the grain and straw ; the other 30 

 parts would probalily largely if not entirely be found in the 

 roots. For every 100 parts of nitrogen applied in the form 

 of dissolved leather 39 parts were returned, while for every 

 100 parts applied in the form of Philadelphia tankage but 5.3 

 parts were recovered. The next column shows that, if the 

 amount of nitrogen returned in case of the nitrate of soda 

 pots be represented by 100, then the amount returned in case 

 of dissolved leather would be 56, and in case of Philadelphia 

 tankage 7.6. The last column indicates the parts of grain 

 produced for every 100 parts of straw. Notice that where 

 no nitrogen was applied only 21.6 parts of grain were pro- 

 duced to 100 parts of straw ; but when .30 gram of 

 nitrogen in form of nitrate of soda was added, 36 parts of 

 grain were obtained to 100 parts of straw. 



Resume. — Action of Sulphuric Acid on Leather. 



Artificial digestion tests show that nitrogen in either raw, 

 steamed or roasted leather, after being acted on by 50° B. 

 sulphuric acid, has a digestibility of 70 per cent. This test 

 would class it, as regards availability, with the average qual- 

 ity of animal matter sold for fertilizing purposes. 



The result of our first year's test with pot experiments 

 indicates that, when nitrate of soda as a source of nitrogen 

 is rated at 100, the nitrogen in the form of dissolved leather 

 would be rated at about 60. The return from the Philadel- 

 phia tankage was very slight. The experiment will be con- 

 tinued the coming year. 



