22 



NATURE 



{Nov. I, 1888 



' 



This conclusion is based upon observations extending over 

 upwards of forty years, and has been rather forced upon the 

 attention of Sir John Lawes, than assumed in the first instance. 



The central position of Hertfordshire (at least with regard to 

 England), and the medium character of the soil and climate, 

 aflford some reason for expecting an average yield ; and the 

 various treatments to which the selected plots have been subjected 

 also assist to secure an average and representative result. The 

 selected plots are five in number, each of which has been similarly 

 treated for the last forty-five years, and all of them have carried 

 wheat every year during this long period. One of these plots 

 has remained continuously unmanured and has yielded on an 

 average 13 bushels per acre, which, strange to say, is one bushel 

 above the official average crop of the United States of America. 

 One has been continuously manured with fourteen tons of farm- 

 yard manure per acre, and has yielded an average of 33! bushels 

 during the last thirty-six years. The remaining three selected 

 plots have been treated with artificial manures upon a uniform 

 and undeviating plan, and have yielded on an average respec- 

 tively 32f, 36^, and 36^ bushels per acre taken also over a 

 period of thirty-six years. 



The mean average of all these five plots taken over this long 

 period is 27I bushels, and it is this mean which corresponds with, 

 or at least closely approximates to, the average yield of the 

 United Kingdom. The average yield of these five selected plots 

 for the present year is 27I bushels per acre, equal to 265 bushels 

 when calculated as of 61 pounds each. The average yield 

 arrived at on the same principle last year was 28 1 bushels per 

 acre, showing a deficit this year as compared with last of 

 i^ bushel per acre. Agiin, comparing the result obtained from 

 the Rothamsted standard plots with what is considered the usual 

 standard avera;^e of 28 bushels per acre, the deficiency for the 

 present year would appear to amount to ig bushel per acre only. 

 Sir John Lawes's general deduction that the selected plots at 

 Rothamsted fairly represent in yield the average of the United 

 Kingdom is certainly an assumption which might be objected 

 to on scientific grounds. It is, however, as already pointed out, 

 rather to be regarded as an ascertained fact than as a simple 

 assumption, and from the evidence of a large number of years, 

 the fluctuations of yield at Rothamsted may be regarded as a 

 barometer, if we may so express it, of the parallel fluctuations 

 throughout the United Kingdom. 



Judged by the standard of the Rothamsted yields, the wheat 

 crop of 1888 is only slightly below the received average of 

 28 bushels per acre. 



It is well known to agriculturists that the harvest of 1879 was 

 the worst which the present generation has witnessed, and 

 during the dismal summer which has now ended, many persons 

 expressed an opinion that the harvest of 1888 was likely to equal 

 in badness that of 1879. This discouraging view has, however, 

 happily been dispelled, and the harvest of 18S8, although in- 

 ferior in both quantity and quality to an average one, is not to 

 be reckoned as disastrous. 



One important feature of the harvest of 1888 is, however, its 

 irregularity, and this has not only given rise to many conflict- 

 ing opmions, but made it exceedingly difficult to arrive at the 

 truth. 



The opinion of Sir John Lawes is that upon farms where the 

 condition of the land was defective, as well as upon all lands 

 where there was an excess of artificial nitrogenous manure, there 

 was less than the average produce ; but that when the manurial 

 conditions were more favourable there was more than an average 

 produce. Thus the continuously unmanured plot yields only 10 

 bushels per acre instead of 13, the average of the preceding 36 

 years. The farmyard manure plot, on the other hand, yields 38 

 bushels, against an average of only 33^ bushels. Lastly, the 

 plot which receives an excessive amount of nitrogenous manures 

 in the form of ammonia salts, as well as mineral substances, 

 yields only 35^ bushels, against its average of 36J bushels. The 

 result thus generally indicated is supported by experiments made 

 beyond the list of the usually selected plots, and is in these 

 experiments still more pronounced. 



The economic conclusion arrived at by Sir John Lawes after 

 carefully passing this evidence in review is that " Taking the 

 average population of the United Kingdom for the harvest year 

 1888-89 at rather over 37^ millions, the estimated requirements 

 for consumption, at 5 "56 bushels per head, would be about 26g 

 million quarters. The area under wheat is reported to have 

 been 2,663,436 acres, or nearly 300,000 acres more than last 

 year. This area, at 26g bushels per acre, would yield nearly 9 



million quarters (8,947,480), and deducting 2 bushels per acre 

 for seed, there would remain rather over 8j million quarters 

 (8,281,621) available for consumption, and there would therefore 

 iae required about 18^ million quarters (18,394,271) to be pro- 

 vided from stocks and import. It is admitted that the wheat 

 crop not only of America, but of some other countries whence 

 we derive supplies, will be below the average. But during the 

 last two months of the past harvest year our imports were at the 

 rate of 21 million quarters per annum, and there seems no reason 

 to fear that there will be any difficulty in obtaining sufficient 

 supplies." 



ON THE INFLUENCE OF LIGHT UPON THE 



EXPLOSION OF NITROGEN IODIDE} 

 'T'HE statement of L. Gattermann in his recent paper {Berichte 

 -*■ d. detitsch. chein. GescUsch. xxi. 751 ; following up V. Meyer's 

 paper in the same volume, p. 26) on nitrogen chloride, that its 

 explosive decomposition may be brought about, or its suscepti- 

 bility to explosion much increased, by exposure to bright light, 

 has recalled to my mind the fact, which did not specially impress 

 me at the time, that I myself undoubtedly observed the same 

 relation several years ago in the case of nitrogen iodide. 



In a paper on the preparation and composition of the latter 

 substance, published in the first number of this Journal (April 

 1879), it was noted that on two occasions the product obtained 

 with the composition NI3 or Nglg "exploded in some quantity 

 tiiide)- water with much violence and complete shattering of the 

 vessel." 



I remember distinctly that in one of these cases I had just 

 carried to a window, through which the sun was shining, the 

 beaker full of water at the bottom of which was the black 

 sediment of iodide, and was gently stirring the liquid with a 

 glass rod, holding the beaker up so as to look at it from below, 

 when the rod touched the lower part of the side or the bottom 

 of the vessel, and the explosion occurred. 



In the other case the iodide was being washed with ice-cold 

 water of ammonia, the vessel standing on a table exposed at the 

 time to the direct rays of the sun. I do not remember with 

 certainty what seemed to precipitate the explosion on this 

 occasion, but I believe it was the pouring some fresh liquid, 

 from the height of a few inches, on the black sediment of 

 iodide which had just been partially drained by decantation. 



Under ordinary circumstances nitrogen iodide, while wet, 

 exhibits no extraordinary sensitiveness, and may be safely worked 

 with, only becom'.ng highly dangerous on drying, so that I have 

 little doubt that bright sunshine was influential in bringing about 

 these two explosions. J. W. Mallet. 



University of Virginia, May 8, 1888. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge.— Dr. Hill, now Master of Downing College, 

 having resigned the Demonstratorship of Anatomy, a senior 

 demonstrator and two junior demonstrators at ;r^ioo and ;^5o 

 stipends, and a University lecturer on advanced human anatomy 

 are to be appointed, providing four teachers for the aggregate 

 stipend, /'250, formerly received by the Demonstrator. _ Star- 

 vation pay this, considering the limited opportunities in 

 Cambridge for supplementing the income of an aaatomist. 



A grant of ;^8o from the Worts Fund is recommended to be 

 made to Mr. M. C. Potter, to enable him to make botanical 

 researches and to collect specimens in Ceylon during the coming 

 winter. 



The old Chemical Laboratory being now vacant, it is to be 

 altered into a Pathological Laboratory for Prof. Roy. 



The new scheme of examinerships in natural science was 

 passed last week ; the chief features being the appointment of 

 two examiners each in elementary biology and chemistry, to 

 take the 1st M.B., and the "specials" for the ordinary B.A. 

 The stipends are rearranged, and in addition to a fixed 

 amount a proportionate sum per candidate is allotted to the 

 examiners, 5^-. for Tripos candidates, 4f. for 2nd M.B. 

 physiology and anatomy, and 25. for the rest. Thus the 

 examiners in anatomy and physiology, if loo candidates 

 J Reprinted from the American Chemical Jou?nal, vol. x. No. 4- 



