400 



NATURE 



[August 27, 1903 



and Germany. In this country calcium phosphate occurs 

 in the form of coprolites, supposed to be the excreta of 

 extinct saurians, in Cambridgeshire and elsewhere. All 

 these natural phosphatic mineral deposits are mined, and 

 have become valuable assets to the countries possessing 

 them. The conversion of the minerals into a form suitable 

 for the nutrition of crops is a branch of chemical industry in- 

 volving the use of sulphuric acid for the conversion of the 

 natural phosphate into the more easily assimilable form 

 known as superphosphate. The greater part of the world's 

 output of natural phosphates finds its way to Germany 

 to undergo this treatment, the annual consumption 

 of artificial manure in that country being estimated 

 at something more than two million tons at a cost 

 of about 5,ooo,oooZ. The mineral portion of the bones 

 of animals, as you are no doubt aware, also consists 

 largely of calcium phosphate, and before the mining of 

 the mineral phosphates the conversion of bone ash into 

 superphosphate was carried on on a very large scale. Bone 

 ash is supplied now in large quantities from South America, 

 but not much is converted into superphosphate, as the 

 bones, after removal of the fat and the size (for glue), are 

 capable of being finely ground, and are available for manure 

 in this form. 



Here is surely a romance of chemistry ! The phosphates 

 contained in the vegetation of the South American pampas 

 go to build up the bony framework of the cattle which 

 graze thereon. The skeletons of these beasts ultimately 

 supply, let us say, the growing crop of a beet sugar manu- 

 facturer in Germany with phosphates. The phosphates 

 picked out of the soil by South American vegetation con- 

 centrate in the bones of cattle, and are then sent into 

 circulation in German beet. Or, even more striking, the 

 phosphates accumulated by the great lizards of a remote 

 geological age are now circulating through growing crops. 

 This circulation of matter through the intervention of the 

 living organism is an every-day story to the chemist. To 

 our greatest poet apparently it was also known : — 



" Imperious Csesar, dead and turn'd to clay, 

 Might stop a hole to keep the wind away: 

 O, that that earth which kept the world in awe, 

 Should patch a wall to expel the winter's flaw ! " 



But we must descend from romance to reality. The de- 

 posits of sea birds also contain phosphates derived from 

 thf! fish upon which they feed, and these deposits often 

 accumulate in such large quantities as to make them avail- 

 able for agricultural purposes. Under the name of guano, 

 immense quantities of this material, which contains both 

 phosphates and nitrogenous matter, are exported from Peru. 

 There is subject-matter for philosophising here, also, about 

 the circulation of phosphates from marine organisms 

 through birds into growing crops, and so forth, but time 

 will not admit of many side disquisitions if I am to keep 

 to my text. As another source of phosphate, it is of interest 

 to know that the basic slag obtained in the Thomas- 

 Gilchrist process of making steel is now largely used, so 

 that the work set going by Liebig has, among its latest 

 developments, led to the utilisation of a waste product of 

 the steel industry. 



Excepting in the case of leguminous plants, which are 

 capable of utilising atmospheric nitrogen by a process which 

 it does not come within my province to explain, the ordinary 

 source of nitrogen for growing plants is a soluble nitrate, 

 and if the soil is poor in such salts, they must be supplied 

 either directly or indirectly through salts of ammonia, 

 which are converted into nitrates in the soil bv bacterial 

 action in a way that nobody is better able to explain to you 

 than Prof. Warington. The great natural deposits of 

 sodium nitrate which occur in Chile and Peru supply prac- 

 tically all the nitrogen applied to the soil in this form for 

 fertilising purposes. With respect to ammonia, the de- 

 structive distillation of coal for the manufacture of gas and 

 tar products, or for the production of coke, furnishes prac- 

 tically all the salts of this base required for agricultural 

 and other purposes. The vital importance of assimilable 

 nitrogen to growing crops has led the chemist also to study 

 methods for the fixation of atmospheric nitrogen so as 

 to rendeV this element available for such purposes. It has 

 long been known that nitrogen and oxygen can be made to 

 combine under the influence of the electric spark. This, 



as you may remember, is one of the methods used by 

 Cavendish in his classical researches on the composition 

 of the air, and it was used also by Lord Rayleigh to separate 

 atmospheric nitrogen from argon. Sir William Crookes 

 has shown that the combustion can be brought about by 

 the electric flame with such facility as to render the pro- 

 duction of nitrite and nitrate by this process an industrial 

 possibility, and the manufacture has actually been started 

 in America by utilising the Falls of Niagara for the gener- 

 ation of the necessary electric power. Still more recently 

 it has been found by Caro and Frank that when lime and 

 coal are heated in the electric furnace, the calcium carbide 

 fixes atmospheric nitrogen to form a compound known as 

 calcium cyanamide, and this decomposes in the soil with 

 the liberation of ammonia, so that the nitrogen of the air 

 is thus rendered available for plant nutrition by an electro- 

 chemical process. The manufacture of this " Kalkstick- 

 stoff " is in the hands of the electrical engineering firm of 

 Siemens and Halske, in Berlin. 



There has been no straining of facts on my part in this 

 sketch — necessarily brief — of the industrial results of 

 Liebig's work. The establishment of the fundamental 

 truths was a piece of pure scientific research. Had it not 

 been made known by the irrefragable proofs furnished by 

 scientific method that such and such elements were essential 

 for plant growth, the mineral resources of the earth would 

 have remained unused for this purpose. The minute per- 

 centage of nitrogen locked up in the fossilised vegetation 

 of the Carboniferous period would never have been isolated 

 in the form of ammonia and applied to the soil for the 

 nourishment of the crops raised by the present day agri- 

 culturist. The successful cultivation of the beet as a 

 source of sugar has been made possible by this knowledge, 

 and it may be of interest to add that the further scientific 

 study of the cultivation of that root in Germany has led 

 to the yield of sugar being increased from 5J to 13 per cent, 

 during the period commencing about the year 1840 and 

 ending at the present time. The economic result of this 

 industry upon our own sugar-growing colonies is a fiscal 

 question which does not come within the province of this 

 address. 



Equally instructive as illustrating the connection between 

 scientific research and industry is the production of alcohol 

 and other valuable products through the agency of living 

 organisms. The spontaneous conversion of saccharine 

 solutions, such as the juice of the grape, into solutions con- 

 taining alcohol, with the concurrent development of gaseous 

 carbon dioxide, is among the earliest recorded observations 

 in applied organic chemistry. The various theories which 

 were from time to time advanced to explain what is called 

 " fermentation " are now of historical interest only. It is 

 to the researches of Pasteur that we are indebted for the 

 placing of the fermentation industries on a scientific found- 

 ation. This illustrious chemist, who as far back as 1860-62 

 had successfully disproved the so-called " spontaneous 

 generation " by showing that the ordinary air was always 

 charged with living germs, turned his attention to the 

 diseases of wine, with the object of assisting an industry 

 of great national importance in France. His " Etudes 

 sur le Vin " was published in 1872. A greater work — the 

 great classic of the science of fermentation — appeared in 

 187G under the title " Etudes sur la Bi^re." In this work 

 it was definitely proved that the transformation of sugar 

 into alcohol is a biochemical change ; that the yeast which 

 produces this change, and of which the organised nature 

 had long previously been suspected, is, in fact, a low form 

 of vegetable life allied to the fungi, and that it multiplies 

 and grows at the expense of the sugar and other materials 

 contained in the fermenting liquid, the alcohol and carbon 

 dioxide being the products of its activity. It is now known, 

 through the work of Buchner, that this chemical trans- 

 formation of sugar into carbon dioxide and alcohol is the 

 result of interaction between the sugar and a certain definite 

 substance — an unorganised ferment — which is formed by 

 the living yeast cell, and which can do its work indepen- 

 dently of the cell in which it originated. 



The scientific development of the fermentation industries 

 followed from this and other work of Pasteur's. The 

 names of those who have taken part in these later develop- 

 ments are numerous and illustrious, but want of time pro- 

 hibits a detailed survey of this most fascinating chapter 



NO. 1765, VOL. 68] 



