410 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



secretions of more than from twenty to twenty-five persons. 

 On this scale, London would require a farm of 150,000 acres 

 to utilize its refuse. 



The difficulty of irrigation with sewage lies in the fact 

 that the purification and economical application generally 

 go together. Purification alone is quite practicable, although 

 at great expense ; and economical utilization alone can occa- 

 sionally be secured ; but the attempt to combine both in a 

 general way, and at the same time effect a result free from 

 sanitary objections, and one that shall pay expenses also, is, 

 in his opinion, entirely impossible. 1 A, May 16, 1873, 240. 



ACTIOX OF MANURES OX THE GROWTH OF PLANTS. 



Messrs. Masters <fc Gilbert have been investigating the ac- 

 tion of manures in favoring the growth of certain species of 

 plants; and for this object twelve different series of meadow 

 plants were grown separately, in wooden boxes, both without 

 manure and with five different manures, such as manures 

 furnishing phosphates, potash, etc., ammonium salts, sodium 

 nitrate, ashes and ammonia, and ashes with sodium nitrate. 

 The soil employed was thought to have been too rich, and 

 the results of the observations of the two seasons Avere some- 

 what contradictory. Of the three clovers, Trifolium pratcnse 

 and repeiis were in the first seasons much benefited by the 

 manure, while Lotus cornicidatus seemed actually injured. 

 In the second season the ash alone had little effect on the 

 clovers ; but in both seasons nitrogenous manures, with oth- 

 ers, produced the largest crops. \ith six kinds of grasses 

 the ash manure alone had little effect ; and in almost every 

 case the best growth was from a mixture of ashes with nitro- 

 gen. Observations on the development of roots induced the 

 opinion that those plants which dispossess others under liberal 

 manuring are those whose habit of growth gives them the 

 widest hold on the soil. 21 ^, Jiay, 1873, 522. 



NITROGEN IN FERTILIZERS. 



Professor Hellriegel made a series of experiments to ascer- 

 tain whether fertilizers should, necessarily, only restore to 

 the soil the mineral ingredients removed with the crops, as 

 Liebig contended, the atmosphere being relied upon for the 

 nitrogen ; or whether, as Stockhardt considered experiment- 



