98 



Post, explains the Brazilian treatment of the latex, and goes on to 

 say: "It is, however, most noticeahle and, according to the ex- 

 ])erience of Trillat and other investigators, that wood smoke 

 contains another suhstance (besides creosote) having strong con- 

 serving properties, namely, formaldehyde, which, dissolved in 

 water, is the formaline or formal of commerce. It was there- 

 fore thought probable that this stuff would be found in small 

 quantities in smoked rubber. This was, indeed, found to be so. 

 With the help of various sensitive reactions, I could undoubtedly 

 show the presence of formaldehyde in smoked rubber sheets so 

 that bv reason of this result it mav be taken that the conserving 

 work of smoke on rubber must at least be partly attributed to the 

 presence of formaldehvde in the smoke. In the development of 

 smoke, it would be well to bear this in mind, by endeavoring to 

 eet a smoke that is as rich as possible in formaldehyde. Now 

 it has been found that organic substances, for instance, susfar, 

 will, through incomplete combustion, produce more formalde- 

 hvde when they are placed in contact with metals. From this 

 we may also conclude that smouldering wood in contact with a 

 metal, such as iron, will give a smoke with a higher percentage 

 of formaldehvde thtin when that contact with a metal does not 

 exist. The wood must smoulder ; therefore, it must burn with- 

 out flpme. and this is onlv attained by limitinsf the admission of 

 air. If there is too much air, less smoke is obtained and more 

 fuel is used ud ; so that it is less economical from two points of 

 view. It might be well also for planters to bear in mind that in 

 smoke a poisonous eras, the well-known carbonicoxida is formed, 

 of which the relative quantitv increases under the last-named 

 conditions. From a hygienic point of view, the health of the 

 coolies working continually in an atmosphere of smoke should 

 be considered. Whether smoking has a direct influence on the 

 nhvsical properties, for instance, on the elasticitv of the product, 

 I should not dare at present to decide. As a fact, it can onlv be 

 said now that smoked rubber keeps better and is not so liable to 

 mould as unsmoked rubber. As a rule, a higher price is paid for 

 smoked rubber on this account." 



CULTURAL DIRECTIONS FOR PAlWY.l. 



P.v P. T- Wkstku, Horticulturist. 



The PhiHp]Mncs Pureau of Agriculture has issued the follow- 

 ing directions for growing pawpaws which should jirovc of iji- 

 terest and he useful to Ceylon residents, says the Tropical .li^^ri- 

 culturisf. There are not nearly enough pawpaws gi-own in 

 Ccvlon. 



Ski:i) P.I'.I). — The seed bed should be ])repared by thordUgliK- 

 l)ulvcrizing the soil by spading or hoeing the ground well, and 



