530 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



were calculated by the usual formula. The results show that if six borings 

 are made of a soil under investigation and the boring? mixed to form a composite 

 sample there is a 4 to 1 probability that the accuracy of a duplicate mechanical 

 analysis of the composite sample will be within 5 per cent, of the true value, and 

 there is a similar probability that the chemical analysis will be within 8 per cent, 

 of the true value. An increase in the number of borings does not markedly 

 reduce the probable error. — /. E. IF. E. H. 



Sanseviera Laureiitii. By M. J. Gerome {Jour. Soc. Xat. Hort. Fr. Jan. 1915, 



p. 14). — This is a variegated form of S. guineensis discovered in the Congo by 

 Prof. Laurent. The variegation reappears in plants reproduced by division 

 of the rhizome, but the writer finds that plants raised from leaf-cuttings revert 



to the type S. guineensis. — M. L. H. 



Seeds, Growth of, in Heat compared with Growth in the Open. By M. M. 



Cure and Foex (Jour. Soc. N at. Hort. Fr. July-Dec. 191 4, p. 500). — The observa- 

 tions of horticulturists that certain vegetables heart when sown in hot-beds, 

 whereas they run to seed when sown in the open or in a cold frame, have caused 

 some experiments to be made. 



Tables are here given showing the relative growth of root and plant produced 

 by turnip and chicory seed sown — (1) in the open, (2) in cold frames, (3) in 

 a hot-bed. From these it appears that root growth takes place much more 

 slowly at first in heat, which, on the other hand, produces leaves much earlier. 

 The total length of the plant is at all times greater in heat, and at a later stage the 

 roots also show a great increase in size over those produced without it. — M. L. H. 



Senecio glastifolius {Bot. Mag. tab. 8624). — South Africa. Family Com- 

 positae. Tribe Senecionideae. Herb, perennial, erect, 4 ft. high. Leaves linear, 

 3 in. long, \ in. wide. Heads 2 in. across. Ray florets rose-lilac. Disk vellow. 



G. H. 



Simples. By P. de Yilmorin {Jour. Soc. Xat. Hort. Fr. Jan. 1913, p. 52). — 

 A review of a dictionary of botanical synonyms collected with the most laborious 

 care from the works of the sixteenth and later centuries. The scientific name 

 of each plant is traced through all its changes in successive periods, the present 

 form being sometimes but a slight variation on that given by the old herbalist, 

 and sometimes having had to be entirely altered in consequence of more scientific 

 classification. — M. L. H. 



Soil Acidity, A New Test for. By E. Truog (U.S.A. Agr. Exp. Stn., 

 Wisconsin, Bull. 249, Feb. 1915, pp. 1-16 ; 4 figs, and 1 plate). — It is stated that 

 two-thirds of the soils of Wisconsin are acid, though the degree of acidity varies 

 considerably. In some cases the soils are so acid that even clovers and lucerne 

 cannot produce profitable crops. Thus the need of a simple test for determining 

 the acidity of the soil is evident. Litmus paper, being affected by carbonic acid, is 

 not entirely satisfactory, nor is hydrochloric acid, as it simply indicates the presence 

 of carbonates. A new test has been devised which indicates not merely the 

 presence of the acids but also the degree of acidity. 



Use is made of the fact that, when acids are placed in contact with zinc 

 sulphide, a gas (sulphuretted hydrogen) is evolved which acts upon lead acetate 

 paper, forming the corresponding lead sulphide, and causes a blacking of the test 

 paper. The amount of blackening will indicate the amount of acid. Applying 

 this to the soil, if a solution of the soil be made with distilled water and some 

 powdered zinc sulphide added, and the mixture warmed, sulphuretted hydrogen 

 gas will be evolved. Its presence may be readily demonstrated by placing 

 strips of lead acetate paper over the mouth of the vessel. The relative blackening 

 of the paper will show the degree of acidity ; the blackest, very strong acidity ; 

 while the slightest colouring will show very slight acidity. 



A convenient form of apparatus is described, whereby field tests may be 

 readily and quickly carried out. — A. B. 



Soil Gases. By J. W. Leather (Jour. Agr. Sci. vii. Part 2, pp. 240-241 ; 

 Sept. 1915). — The writer has subjected samples of Pusa soils to experiment 

 as described by Russell and Appleyard [see abstract in Jour. Roy. Hort. Soc. 

 xli. Part 1, pp. 166, 167, Aug. 1915] and concludes that the gas obtained by 

 Russell and Appleyard was liberated gradually by bacteria. The authors of 

 the original experiments point out in reply that the conditions of their experi- 

 ments have been misunderstood by Leather, and particularly that as in some 

 cases there was practically no interval between the experiments there was no 

 time for the bacterial action presumed to have taken place. The results of the 

 Pusa experiments, in fact, support their conclusions. — /. E. W . E. H. 



