JULV 1, 1885.] 



THE TROPICAL AGRICULTURIST. 



61 



of 10 bales, then evfry factory that wishes to bo pro- 

 perly enlightened hail, only for these barks, to make 867 

 tests. Adit to this the S. American and Javan barks. 

 It is oln-ious that the consequence will be, that small 

 parcels of 1 a 2 bales are neglected, that the manu- 

 facturers examine no samples, -or at least not all the 

 manufacturers, and that the true value is obtained with 

 difficulty for such parcels. By mixing several small 

 parcels, for instance, Ledgeriana and officinalis root-bark 

 in powder, Ledgeriana and officinalis stem-bark of equal 

 contents, also in powder — young plantations, which 

 otherwise would have to supply too many small bulks 

 of various sorts, can thus make np one parcel important 

 enough to attract the attention of buyers. 



If there is enough of each sort to make up 5 or C 

 bales — about 500 kilograms— then it is not necessary to 

 mi.x them. For manufacturers bark the name of the 

 bark is not of the least con.sequence, the only factor 

 that regidates the prices is the proportion of sulphate 

 of quinine it contains. 



I also observed that the harvesting of the bark — 

 especially of the branch bark — was performed rather 

 rudely, and that a good deal of wood was taken along 

 with the bark. In some samples I have found as much 

 as 10 a 15 p. ct. of wood. This ought to be looked 

 to, for it acts very prejudicially for the seller because 

 the buyers will deduct a veri/ full percentage for wood. 



In general the succirubra, offered by private planters, 

 was too young. There is a good demand for these 

 barks, but they must be at least 7 years old, or rather 

 older, and have the white silvery appearance on the 

 outside and the reddish brown colour inside, that are 

 required of this sort, and if these couditions are not 

 complied with, it is of no use cutting the bark in long 

 quills. 



Mor do the shippers in Java usually set the tare of 

 the chesis in which the barks are packed on the outside 

 of the chest. This causes much trouble at Amsterdam, 

 because the chests must then be unpacked there, weighed 

 and be repacked, to state the tare to the buyers. The 

 barks suffer under the treatment, and for all these 

 small operations the charges are relatively high. I 

 therefore advise planters to mark the tare as accur- 

 ately as possible on the outside of the Jchests. 



As subtitutes for the quinine-salts, during 1884, anti- 

 pyrine, a derivative of chinoline, and thalline were 

 recommended. 



Anti-pjTine is a greyish-white, crystalline body, smelling 

 of tar, and having an acrid bitter taste. It possesses 

 ahsohttely no febrifiic/al giia/iti/, but lowers the temper- 

 ature of the body two or three degrees Celsius. The 

 dose is one gramme, and must be repeated from 2 to 5 

 times, at intervals of one hour. The great quantities 

 required to> be taken, render the autipyriue, which 

 costs about t'GO per kilo, very dear. 



Thalline (tetrahydroparachinanisol) has been prepared 

 by Skraup. ^Vith sulphuric and tartaric-acid it yields 

 crystalline salts, which taste acrid and bitter. This new 

 remedy, which has also the quality of lowering the 

 temperature, is now being made the object of experi- 

 ments, 



J. 0. B. MOENS. 



Haarlem, April 1st, 1885. 



MANUrjNG AND CULTH^ATION: PRACllCB 

 WITH SCIENCE. 



Fine v. Coakse Sdpekpiiosphates. — The controverted 

 point as to the relative effects of very finely divided 

 manures and coarsely powdered fertilizers has received 

 some illustration in recent experiments of P. "Wagner. He 

 finds that the degree of fineness of a manure really is of 

 great importance as regards its action in the soil, but that 

 its activity does not necessarily increase with the degree 

 of fineness. As a case in point, he maintains that on soils 

 rich in lime it is preferable to use finely divided super- 

 phosphate, while on soils poor in lime coarsely broken 

 superphosphates give better results. 



Tub Function of Stltca in Plant Growth. — Experi- 

 ments by Dr. Kmil \\'olft on this subject may pos.sible lead 

 to important result,s, for he has been end(^avouring to 

 ascertain how far it would bo practicable in the cultiv_ 



ation of grain crops to enbstitute for the expensivs 

 phosphoric acid the far cheaper silica. The experiment, 

 were made on oats grown by means of water culture 

 that is, in nutrient solutions thi> compositions of which 

 is known and may be modified at pleasure. There were 

 three sets of experiments arranged respectively to in- 

 clude no silica, very little silica, and much silica. It 

 may here be observed that although silica is commonly 

 found m the ash of plants, particularly of grasses and 

 cereals, yet healthy vegetation may be produced in the 

 absence of silica, so that this ingredient cannot be re- 

 garded as essential to plant growth in the same way 

 as nitrogen, potash, and phosphorus are known to be. 

 Woffi's results indicate that the absorption of silica 

 greatly assists the assimilation of other plant foods, and 

 that plants to which silica is supplied show a decidedly 

 better development of grain and straw than do others not 

 so treated. Previous experiments had shown that phosphoric 

 acid similarly acted in facilitating the assimilation of ordmary 

 plant foods, and hence it is suggested whether it would 

 not be possible to replace phosphoric acid by silica,- acid 

 (silica) in the composition of artificial manures. As a 

 matter of fact, manure manufacturers have attempted to 

 achieve this result, and their failure is attributed to us- 

 ing silica in an unsuitable form. Further experiments 

 are needed, eBpecially by ordinary methods of cultivation, 

 as under-water culture plants absorb more nutriment 

 than when grown in the soil. It is doubtful whi-tlier 

 phosphoric acid in manures could be successfully replaced 

 by silicic acid, but it is not unlikely that a combin- 

 ation of both may be obtained, which would yield ex- 

 cellent results in the cultivation of cereal crops. 



iNFLnENuE OP Shelter on Soil Temperature. — Observ- 

 ations byE. AVollny on the temperature of soils under various 

 circumstances show that during the warm season bare soil 

 is much warmer than sheltered soil, and soil sheltered 

 bv straw manure warmer than that covered by grass. 

 At the hour of greatest daily temperature the difference 

 between the temperature of the shaded and exposed 

 soil is greatest, while at the lowest temperature of the 

 twenty-four hours the exposed soil is generally cooler than 

 the sheltered soil. Perfectly analogous results obtain, 

 as is well known, in the case of a sandy desert as compared 

 with a grassy plain. The daily variations of temperature 

 are greatest in exposed soil and least in grass-covered. 

 Soil covered by vegetation or dead vegetable matter, such 

 as stul>ble or manure, is considerably warmer in summer 

 at some distance below the surface and cooler in winter 

 than a fallow, but when a warm period in winter or a cold 

 period in sunmier intervenes the influence of the covering 

 makes itself felt in the opposite direction. Bare soil is iu 

 spring morerapidly heated, and in winter more rapidly cooled. 

 A crop exerts a decided influence on the temperature of the 

 soil, the thickness of sowing and the age and character 

 of the crop being all effective, though it is uncertain 

 whether the plant itself has any influence. Soils are found 

 to warm more rapidly when the crop is drilled than 

 when it is sown broadcast, and a further advantage is 

 gained if the drills .aie wider apart and if they run 

 north and south. In the case of jjerennials, as meadow 

 grass, the temperature rises after mowing. — Adelaide 

 Observer. 



SIR J. B. LaWES on the CULTIVATION OF 

 POTATOS. 



Although I consiilcr that the use of complete artificial 

 manures involves too great a cost for their emi)loyini'utr 

 in the growth of ordinary farm crops, perhaps an exception 

 may be made in regard to Potatos, a crop which requires 

 a large supply both of potash and nitrogen. 



At Rothamsted we have grown nine crops of potatos 

 in succession upon land which for fifteen years previously 

 had received no y.ard manure, and the average yield of 

 the last three crops has been 'lOO bushels per acre, 

 calcidating the bushel to weigh 50 lb. The .manure used 

 each year has been SOU lb. of sid^jhate of potash, ,S50 lb. 

 of superphosphate of limn, anil 401) lb. of salts of antninnia : 

 while in another e.xiieriment, instead of the salts of 

 ammonia, 540 lb. of nitrate of soda were ai)|)li(!d. The 

 produce from both mamtres has been tdmost iiidentical. 



The sulphate of potash supplies about loU lb. of potash — 



