Vol. XIII. Xo. 327 



THE AGRICULTURAL NEWS 



.3.57 



the tenden<-y to ilevelnp new \ai-ieties by mutatinn whicli 

 chmiicterize.s Oenothera La-marckiana. There is a further 

 parallel in the fact that in both cases very similar, if not 

 identical, new characters come into expression at dififerent 

 times and in difterent places. An example of this phenomena 

 in Egyptian cf>tton is afforded by the Xiibari and Yuma 

 ■varieties. 



If the tendency to produce mutants is a result of remote 

 <ir cnniplex hybridization, the mutability of Egyptian cotton 

 might be accounted for upon either of the following grounds: 



(1) the sn|(posed hybrid origin of the type as a whole, or 



(2) later crossing with other types of cotton. 



Ever since mutation V>ecame recotrnized as a factor in 

 the breeding of Egyptian cotton, the following methods have 

 been followed in Arizona: (1) recognition and isolation of 

 desiral)le mutants: (2) selection and comparison, on the pro- 

 geny-row basis, of those individuals among their progeny 

 Avhich e.xpress most fully the desirable characters of the new- 

 type: (3) elimination from the seed-increase fields, jireferably 

 before blossoming liegins, of the aberrant and otherwise 

 undesirable individuals. {Journal of Agricultural Research 

 f..r -Tuly li)14.) 



ABSORBENT EARTHS. 



In ronufxion with the article that appears on this page 

 under the heading Boiler Covering, the following note on 

 the origin and composition of, and commercial demand for, 

 siliceous earths may prove of interest. The information has 

 been obtained from two sources: (1) a paper by A. .J. .Jukes- 

 Browne and Prof. .J. 11. Hairison on the geology of Barbados 

 {Quarterly .Journal of the (leological Society, Vol. XLVIII, 

 Part 2, 190, p. 170); and (2) Diatomaceous Earths 

 (Kieselguhr) and Theii Utilization (Bulletin of the Imperial 

 Institute, Vol. III. 190.-), p. .Sf<). 



.Siliceous earths, known in various places under the names 

 Infu.sorial, Radiolarian and Diatomaceous (Kieselguhr) earths 

 are widely di.stributed throughout the world, though the 

 most important deposits, commercially, are tho.se that 

 occur in Oerrnany. In Barbados, according to refer- 

 ence (1) noted above, there are 'some beds consisting of 

 77 per cent, of organic silica with only 0'3.5 per cent, of 

 calcareous matter. These are the well-known infusorial oi- 

 radiolarian earths, composed almost entirely of siliceous 

 organisms^radiolaria, diatoms and sponge-spicules, the' 

 broken debris of these remains forming a matrix in which 

 more perfect specimens are scattered. Associated with these 

 beds are layers of felspathic and jjumiceous .sand or dust, and 

 some of them are rendered gritty Ijy the intermixture of such 

 material. Other beds are so fine, soft, and slightly consoli- 

 dated, that specimens of them are as light in the hand as 

 lumps of pumice. Their exposed portions are generally 

 white, though below the surface they are often yellowish 

 drab, pink, or streaked with these colours.' 



The economic applications of 'infusorial' earth as an 

 absorbent, e.g. in the manufacture of dynamite and polishing 

 material, and as a non-conductor of heat, are well known. 

 A way of applying the Barbados material locally is shown in 

 the aecontpanying article. Apart from this, the present 

 European situation might render its exportation jirotitable if 

 it were found to possess properties superior to those earths 

 <if a similar nature in Scotland and in the Dominions. 

 According to the Imperial Institute, the chief ditWculty in 

 shijiping infusorial earth is the larg'.- Ijulk it cx-cupies in pro- 



portion to its w^eight. Kieselguhr has been imported from 

 Germany and Norway at prices varying from £3 to £,i 

 per ton. 



BOILER COVERING. 



A useful non-conducting covering for boilers and steam- 

 pipes can be made from Barbados infusorial earth, the use of 

 which is calculated to result in considerable economy in 

 steam and fuel. This infusorial earth can be purchased in 

 quantity in Barbados through the usual commercial channels 

 at a cost of about f S'-tO per ton. 



In order to u.se infusorial earth for this purpose a suffi- 

 cient quantity is allowed to soak in water for several hours, 

 preferably over night; the exce.ss of water is poured off, 

 leaving a mixture of infusorial earth and water of a consist- 

 ency convenient for working. To this a mixture of shredded 

 coco-nut fibre and shredded felt is added in sufficient i|uan- 

 tity to hold the mass together in a sort of plaster, and the 

 whole is well worked to mix it intimately. 



The boiler or steam pipe to be coated is prepared by 

 being well scraped to remove rust and dirt, and is then 

 painted over with a coating of red oxide of iron paint and 

 allowed to dry. 



If a number of strands of barbed iron wire are wrapped 

 round the boiler or pipe they att'ord an excellent hold for the 

 coating, and enable it to adhere better. 



The boiler or pipe being thus prepared, it is washed over 

 with a mixture of infusorial earth and water, of about the 

 consistency of thin cream, and' the covering mixture is then 

 applied in thin layers uniforndy over the surface, successive 

 layers being put on until the coating is l.V to 2 inches 

 thick. Each layer should be allowed to dry partially before 

 the next is applied. 



In the case of a Hanged pipe, it is generally found best 

 to cover the pipe up to the level of the flanges, which should, 

 however, not be completely covered, otherwise it is ditficidt 

 to find them should it become necessary to eflect repairs. After 

 the last layer of coating has been applied, the whole surface i.s 

 washed over with a mixture of infusorial earth and water, 

 similar to that mentioned above. This serves to till any 

 holes or o'evices, and gives the exterior a smooth, neat 

 appearance. 



If desired, a lagging can be placed over the coating. This 

 lagging or final covering may be either fine galvanized wire 

 sjauze, canvas, or good sacking. 



It ha:> sometimes been remarked that w^hen a coating of 

 this kind has been removed, the iron surface that has been 

 covered has a, rusted appearance, and fears have been expressed 

 that the surface has been corroded. Experience has shown 

 that if dear, riiaterials free from salt are used, no corrosion 

 takes plac(- from this form of covering. 



At a meeting of the Board of Agriculture of Briti.sh 

 ("iuiana, held in Ge<irgetown, Demerara, on October 16, 1914, 

 I'rofessoi- Harrison informed the Board that the Veterinary 

 Cfimmittee had reported a very severe outbreak of swine 

 fever on thi- East Coast. The Board had taken what steps 

 rtiey could to restrict this pest, and from all they could learn 

 they had been fairly successful. The Professor, accompanied 

 by Mr. .V. Seton Milne, Government Veterinary Surgeon, 

 proposed to visit the district in the following week to ascer- 

 tain whether the disease has been stamped out or not. Pro- 

 fessfn- Hi.rrison also reported that the Colony is now free 

 from the disi^ase of mal de caderas, the animals affected 

 lia\ iiig either died or been slaughtered. (The Daily Arfjosy^ 

 Demerara, October 27, 1914.) 



