6o5 



NA TURE 



[Oct. 18, 1888 



mmediately reduced. The great increase in the actual weight of 

 the crop treated with nitrogenous manures, however, completely 

 overrides percentages, and hence the table showing the effect 

 of nitrogenous manures records a great increase of sugar, corre- 

 sponding with the application of nitrogenous fertilizers. Dr. 

 Gilbert says : "I cannot discuss the physiological explanations 

 of the fact that nitrogenous manures have such a marked effect 

 on the production of the non-nitrogenous substance — sugar." 



It would also be an interesting physiological question why the 

 percentage of sugar is highest when no nitrogenous manure is 

 applied, and also why nitrogen, even in the form of farm-yard 

 manure, appears to at once lower the proportion of sugar in 

 mangel. Also, why further additions of nitrogen still further 

 lower the percentage of sugar. The percentages stand as 

 follows : — 



Sugar, per cent, {in mangel-wurzel). 



No manure ... ... ... ... ii'4 per cent. 



Superphosphate... ... ... ... 10*4 ,, 



Farm-yard manure ... ... ... 8 - 6 ,, 



Farm-yard manure and sodium nitrate 71 ,, 

 The actual quantities of sugar per acre stand as follows, in 

 pounds : — 



No manure 



Superphosphate ... 



Farmyard manure 



Farm-yard manure and sodium nitrate... 



950 pounds per acre. 

 1028 ,, ,, 

 2513 

 3I09 



Judged by percentages we have a descending series, but 

 judged by actual quantities an ascending series of figures. It is 

 somewhat difficult in the face of the diminishing percentages of 

 sugar caused by the application of nitrogenous manures, to see 

 how the functional powers of the plant to make sugar have been 

 heightened or intensified. Still, Dr. Gilbert says : "A direct 

 connection between the supply of nitrogen to the plant and the 

 formation of non-nitrogenous substances is obvious." Might it 

 not be as truly said, " A direct connection between the weight of 

 the crop and the weight of non-nitrogenous substances contained 

 in the crop is obvious" ? 



We have received a copy of memoranda of the origin, plan, 

 and results of the Rothamsted field and other experiments, 

 which gives an excellent idea as to the work carried on by Sir 

 John Lawes on his Hertfordshire property. Sir John began to 

 experiment on growing crops in 1837, but fixes the actual com- 

 mencement of the Kothamsted Station in 1843, when he 

 associated Dr. Gilbert with himself in carrying out a magnificent 

 series of agricultural experiments. A large staff of chemists and 

 assistants are employed entirely at Sir John's own cost, and he 

 has provided for the continuance of the work after his death by 

 setting apart £"100,000 for the purpose as well as sufficient land 

 for carrying out his intentions. It is pleasant to find Sir John 

 Lawes and his indefatigable coadjutor Dr. J. H. Gilbert still 

 young in mind and constitution, and able to throw all their old 

 ardour into their work. 



FLETCHER'S COMPRESSED OXYGEN 

 FURNACE. 



'THE use of oxygen with coal-gas in a laboratory furnace has 

 up to the present been attended with serious difficulties, 

 owing to the intensely local nature of the heat obtained, and the 

 consequent perforation and destruction of crucibles and other 

 vessels. 



In this furnace, diffusion of the heat is secured by using a fine 

 jet of Brin's compressed oxygen directed centrally into one end 

 of a tube a quarter of an inch in bore, open at both ends, the 

 oxygen jet acting as an injector, and drawing with it from four 

 to eight times its bulk of air, the proportion depending on the 

 size of the oxygen jet. This tube, containing the mixture of 

 oxygen and air, is used as the central part of an ordinary blow- 

 pipe of heavy cast-iron, which is placed close up against the 

 burner-opening of one of Fletcher's ordinary injector furnaces, 

 lined with a specially refractory material. 



The power of the furnace depends entirely on the quantity of 

 oxygen and gas supplied, and can be adjusted to any power 

 from a dull red, which can be maintained for many hours 

 steadily, without attention, to a heat which will "drop" the 

 most refractory crucible in less than five minutes from the time 

 the gas is lighted. 



When working at moderate temperatures, the furnace is suf- 

 ficiently quiet to admit of its use on a lecture-table, but at its 

 highest power the noise is considerable. 



There is no difficulty in adapting the burner to other forms of 

 furnace, provided it is found possible to produce satisfactory 

 casings to withstand the heat ; those made for the crucible fur- 

 nace stand, as a rule, exceedingly well, but with alterations in 

 form great difficulties are introduced, more especially with 

 muffles, which, as at present made, will not stand any sudden 



heat, nor will they hold their shape at any temperature ap 

 proaching whiteness. The burner alone will be useful in heat- 

 ing many substances in the open, but, owing to the broad and 

 diffused flame, it is of little practical value for blow-pipe work. 



The special advantages of the apparatus are that it is entirely 

 self-acting, requires no attendance, and that it greatly increases 

 the range of temperatures which can be obtained by any simple 

 apparatus. The largest size at present made takes crucibles not 

 exceeding 3 inches high. 



FOREST CONSERVANCY IN CEYLON. 



(""OLONEL CLARKE, the Acting-Conservator of Forests in 

 ^- x Ceylon, in his Report for last year says that since attention 

 was called in 1873 t0 tne gradual destruction of forests in Ceylon 

 efforts have been made to check the evil. At first the expense was 

 the great obstacle. The Government did not see its way to expend 

 the large sums that would be necessary before the forests could 

 be regarded as self-supporting. However, in 1885, " The 

 Forest Ordinance " was passed, under which certain areas of 

 forest lands were acquired by the State and made State forests, 

 the owners of those areas or persons having any interest in them 

 being compensated for the loss of their rights. These tracts 

 were to be clearly marked out, and, where necessary, replanted 

 and improved. It is yet too soon to say what the effects will be 

 of this systematic treatment, but the Government hopes that a 

 constant supply of good timber will be at hand, and that the 

 climate of the island will be benefited by increased care of the 

 forests. Forests, Colonel Clarke says, make the climate more 

 equable, increase the relative humidity of the air, and perhaps 

 increase the rainfall. Furthermore, the water-supply is regulated 

 by forests, the springs being more regular and sustained, and the 

 rivers more continuous in their flow. Adjacent fields are pro- 

 tected by them and the speed of the wind is reduced. In tropical 

 countries especially, where, during the wet season, the rain falls 

 in torrents, forests are useful in preventing the soil from being 

 washed away into the rivers and bays. Besides, it is confidently 

 expected that a substantial revenue will be derived from the sale 

 of timber, fuel, &c. India, which, relatively speaking, has not 

 more valuable forests than Ceylon, yielded in the year 1883-84 

 a gross revenue of ,£1,052,190, representing a clear profit of 

 £403,815. In the past the native forest-keepers connived with 

 gangs of natives who plundered the forests and deprived the 

 island of the revenue that would otherwise have accrued. The 

 evil effect of the destruction of forests that was so very common 

 until quite recently in every quarter of the globe, is apparent 



