NA TURE 



[May 3> 1906 



of our ovens and kilns is singularly incomplete, and 

 the statement is made that, owing to the nature of 

 the English earthenware bodies, the firing of on- 

 glaze decorations in the continuous kiln has been a 

 failure, when, as a matter of fact, many of these 

 kilns are in successful operation. The treatment 

 accorded to our English bone-china is just as in- 

 complete. 



The accounts of French and German processes are 

 naturally much better, not only because the author 

 is better acquainted with them, but no doubt because 

 so much more has already been published about them. 



The author had the excellent idea of adding to his 

 volume a vocabulary of technical terms in German, 

 English, and French, and tables showing the relative 

 importance of the industry in various countries. Un- 

 fortunately, the idea has been very imperfectly 

 executed. In the vocabulary many of the English 

 terms are such as no potter would use, while some 

 few of them are nonsense ; and the figures given as 

 to the extent of the industry in various countries are 

 so incomplete and incomparable as to be positively 

 misleading. On the whole, however, the book must 

 be described as excellent for its purpose ; and the 

 English potter might well wish that he had such a 

 book to put into the hands of the young men who 

 are likely to occupy responsible positions on his works. 

 \\'iLLi.4M Burton. 



THE SOIL AND ITS TILLAGE. 

 Agriculture Genirale. Le Sol et les Labours. By 



Paul DifHoth. Pp. xii + 490. (Paris: J. B. 



Bailliere et Fils, 1906.) Price 5 francs. 

 ' I ^HIS is the first book of a new French agri- 

 -'- cultural encyclopedia, which is being published 

 in forty volumes, under the direction of M. G. W6ry, 

 assistant director of the Institut National Agrono- 

 mique. It is written bv Prof. Paul Diffloth. The aim 

 of the encvclopsedia is expressed in an introduction 

 bv Dr. Paul Regnard, successor to the late M. 

 Eugene Risler as director of the institute. It is to 

 extract from the present teaching of agricultural 

 science all that is available for immediate application 

 by the practical farmer, making him acquainted at 

 the same time wuth the scientific facts upon which 

 actual practice is based. 



Dr. Regnard pays a compliment to English agri- 

 culturists by stating that they have never accepted the 

 notion which he attributes to his own countrymen 

 that agricultural science is antagonistic to practical 

 experience. We fear the compliment is not altogethei 

 deserved, and that French and English farmers have 

 much in common in, this respect; yet the remarkable 

 progress in the direction of higher agricultural educa- 

 tion during the past ten years in this country may 

 be regai'ded as both cause and effect of the gradual 

 disappearance of the idea that the practice of agri- 

 culture can derive no advantage from the labours 

 and teachings of science. 



With the love of logical anah'sis which characterises 

 French scientific literature, M. Diffloth 's work is 

 divided and subdivided almost ad infinitum. .\n idea 

 NO. 1905, VOL. 74] 



of its completeness may be gathered from a summary 

 of these divisions. The book comprises two maim 

 branches, viz. " .Agrologie " and " The Preparation 

 of the Soil," the former being defined as the study of 

 land in relation to agriculture and of the relationship' 

 which subsists between the nature of a soil and its 

 pioduce. The first branch treats of the soil, the sub- 

 soil, their physical and chemical properties; water in. 

 relation to fertility, its distribution, rainfall, perme- 

 ability, impermeability, water levels, wells, water- 

 courses, &c. ; the analysis of soils by processes 

 physical, mechanical, geological, chemical, &c. ; the 

 relations of the soil with the plant, comprising the 

 subjects of nitrification, denitrification, humus, fer- 

 tility, and the nature of the soil suited to different' 

 plants. The second branch of the book, " The Pre- 

 paration of the Soil," treats of cultivation, the clearing 

 of land, peaty and brackish soils, and the improve- 

 ment of soils by warping, tree planting, levelling,, 

 removal of rocks, stones; tillage operations, including 

 digging, drainage, and the various systems of 

 ploughing; semi-tillage, so called, consisting of 

 scarifying, cultivating (in its technical sense), extirpa- 

 tion of weeds, &c. ; harrowing, rolling; and, lastly, 

 of manures and artificial fertilisers. 



We do not remember ever before to have read anv 

 precise definition of what agriculture is. The author 

 defines it as the art of obtaining from the soil the 

 maximum of substances useful to man at the mini- 

 mum cost. We do not quarrel with such a definition, 

 though it represents the ideal rather than the actual. 

 Full justice is done to the part played by the soil in 

 the sustenance of plants, and in particular to the 

 nitrogen problem, which has been the subject of so 

 much scientific investigation and discussion during 

 the past twenty years. The author indicates briefly 

 the discoveries made by de Saussure, Dumas, Bous- 

 singault, and others as to the action of carbonic acid' 

 of the air and of nitrogen in the soil in the nourish- 

 ment of plants ; the work of mineral salts as demon- 

 strated by Berthier, Sprengel, and Liebig ; the 

 experiments of Schloesing and Miintz showing the 

 action of ferments in transforming organic nitrogen 

 into nitric acid and of micro-organisms in nitrifi- 

 cation ; and, lastly, the experiments of Hellriegel and 

 Wilfarth revealing the existence of bacteria in the 

 nodules found on the roots of leguminous plants and 

 the absorption by their agency of nitrogen from the 

 free and unlimited supplies present in the air. 



M. Diffloth refers to the great developments in 

 France and other Continental countries of the prin- 

 ciple of agricultural cooperation. Its successful 

 application to Ireland is well known, and in Great 

 Britain, too, it is novi- making some headway. The 

 future of agriculture, writes the author, may be 

 summed up in two words as living symbols of its 

 progress and prosperity, " Science et Association." 

 We agree that if " Practice with Science " have been 

 the agricultural watchwords of the nineteenth century 

 signs are not wanting that " Science with Coopera- 

 tion " may be those of the twentieth. 



The practical operations of French husbandry are 

 carefully described, with their scientific significance ; 



