420 RECOKD OF .SCIENCE FOR 1886. 



outcome of whicU will definitely settle the question of the entrance 

 of free nitrogen into vegetable tissues. If this question be answered 

 allirniatively, agricultural science will not place bounds to the possible 

 production of foods. If the nitrifying process does go on within the 

 cells of [)hints, and if living organisms do fix free nitrogen in the soil in 

 a form in w hieh at least a portion of it may be nitrified, we may ex- 

 pect to see the quantities of combined nitrogen increase 2^ari paafsu 

 with the needs of plant life. Thus, intensive culture may leave tlie 

 gardens and spread over the fields, and the quantities of food suitable 

 for the sustenance of the human race be enormously increased. In con- 

 temi)lating the agricultural economies of the future, however, itmust not 

 be forgotten that a certain degree of warmth is as necessary to plant 

 develo[)ment as i)Otash, phosphoric acid, and nitrogen. If it be true, 

 therefore, that tlie earth is gradually cooling, there may come a time 

 when a cosmic athermancy may cause the famine which scientific agri- 

 culture will have prevented. Fortunately however for the human race 

 the cereals, the best single article of food, are peculiarly suitable to a 

 cohl climate. Barley is cultivated in Iceland, and oatmeal feeds the 

 best brain and muscle of the world in the high latitudes of Europe. It 

 is probably true that all life, vegetable and animal, had its origin in the 

 boreal circumpolar regions. Life has already been pushed half-way to 

 the equator, and slowly but surely the armies of ice advance their lines. 

 The march of the human race equatorwards is a forced march, even if it 

 be no more than a millimeter in a millennium. Some time in the remote 

 future the last man will reach the equator. There, with the mocking 

 disk of the sun in the zenith, denying him warmth, flat-headed and 

 pinched as to every feature, he will gulp his last mite of albuminoids in 

 his oatmeal, and close his struggle against an indurate hospitality." 

 (Economical Aspects of Agricultural Chemistry, an Address by H. W. 

 Wiley. Cambridge, 1886.) 



Recent Progress in the Coal-Tar Industry.— Under the above title Sir 

 Henry E. Roscoe delivered a most valuable and interesting discourse 

 at the Royal Institution on Ai)ril 16, 1886. He refers the numerous 

 products, whether dye-stuff's, perfumes, antipyretic medicines, or sweet 

 principles to two great classes of hydrocarbons, the paralHnoid and the 

 benzenoid hydrocarbons. The first is the foundation of the fats, and 

 the second of the essences or aromatic bodies. Petroleum is the source 

 of the first class and coal tar of the second. The following tables give 

 an interesting view of the marvellous products of coal and their relative 

 amounts. 



I. Products of distillation of 1 ton of Lancashire coal: 

 10,000 cubic feet gas. 



20 to 25 gallons anuuoiiiacal liquor (;V T\v.). 

 1-i gallons of ci>al-tar (:= l'.V.).2 ))i)umi1s, s]»oeifie gravity, 1.16). 

 i:nHindred\voigIit of coke. 



