EXPERIMENTS ON TURNIPS. 3 19' 



110° to 112° C. in an oil bath till it ceased to lose weight, and this 

 determination was generally checked by repetition. In this part 

 of the work I am much indebted to Dr Aitken, who very kindly 

 gave me the benefit of his experience in the analysis of turnips. 

 He also visited the experimental plots in the autumn of 1882, 

 and helped to select a piece of ground for the experiments of 

 1883. 



Nearly 400 bulbs were analysed, or about 2 per cent, of the 

 weight of the crop. The resources of the laboratory did not allow 

 of very many analyses proceeding at once, and after these were 

 analysed the turnips in the pits w^ere found to have grown so 

 much in the mild winter that the analysis of fresh samples was 

 not thought advisable. More bulbs than this would have to be 

 analysed to get at the absolutely correct results for each plot, 

 but the error of the mean results of any five plots should be 

 small. 



Table XV. gives the results of analysis. It has been pointed 

 out by previous analysts that the percentage of ash decreases 

 with the increase of dry matter. This has been found to be 

 generally true in the bulbs analysed from these experimental 

 plots, and although the relation of the numbers is not definite or 

 regular, they to some extent mutually check each other. An 

 examination of these results leads to the general conclusion that 

 bulbs under 4 lbs. weight differed little in composition, and very 

 few bulbs in the samples selected from the undunged plots 

 exceeded this weight. Indeed, the variations in turnips under 

 this weight are so small that they cannot be ascribed to the 

 manures applied with much certainty. As the bulbs increase in 

 size, the percentage of ash rises rapidly, and the dry matter 

 decreases, but not to a great extent. An additional analysis 

 was made of a lot of selected large bulbs, w^hose average weight 

 was 7 lbs., and the results obtained were 8*0 per cent, dry matter, 

 and in this 8*4 per cent. ash. "Whatever has a tendency to 

 produce large bulbs affects their composition in this way ; but as 

 the limits of dry matter found were 9*2 per cent, in small bulbs 

 and 8 per cent, in very large yellow turnips, that is to say, one 

 turnip of 7 lbs. contained more dry matter than two of 3 lbs., the 

 deductions to be made from the heavier crops on account of 

 additional water are not very great. The composition of these 

 turnips may be examined more particularly as they are affected 

 (1) by the presence of nitrate of soda, (2) by the dissolving of 

 the ])hosphates, and (."») by dung. In doing so, it will not be 

 necessary to repeat the tables alreaily given. Tlius in Table VI I. 

 (1883) if the amount of dry matter per cent, and per acre, and ash 

 in dry matter per cent, from Table XV. besupjdied opposite each 

 plot, and the averages taken, it will be found that the mean 

 results for five plots with nitrate of soda, are dry matter 8*9 



