Gums. Resins, 



108 



A Chemical Test in Coagulating.— -The Scientist gave us practical proof 

 of this with a pan of freshly-tapped latex. Red and blue litinns were immersed 

 in the fresh milk and neither changed colour— the latex was neutral. Then the 

 proper proportion of glacial acetic acid was added to jiast make the milk slightly 

 acid ; the red litmus then immersed remained red and the blue changed its colour 

 to a half tint, neither really red nor really blue— on close inspection in a few minutes 

 the coalescing of the globules could be observed on the surface of the milk. 



"By properly doing this" said the Scientist, "and by using the washing 

 and rolling machines you can tap your milk to-day and have your rubber to-morow 

 dried, creosote coated, and ready to pack. 



The proper proportion of acetic acid to use is not stated hei'e, but it is all 

 given with full particulars in chapter X. of the Para rubber book, to which the 

 reader is referred. The process of coagulation, it can be read therein, precipitates 

 the proteids ; but it does not get rid of them from the dry rubber, where they form 

 3 to 4 per cent, of the whole. This purifying of the rubber must be done by washing 

 it under a constant stream 'of water. " Rubber cannot be washed too well. Wash- 

 ing it Avhile rolling by hand (rolling under a jet of water for instance) takes off 

 the superficial proteids and stops the initial bacterial growth, but hand rolling and 

 mangling do not effect the interior proteids. This must be done in a machine where 

 it is properly disintegrated, rolled and efficiently cleaned." 



Here, as the Scientist finished, the Inventor beamed and smiled a jovial, 

 self-satisfied smile. The chauffeur was already sounding his horn. The Scientist put 

 away his test tubes and wiped his brow ; the Company Promoter made a last entry in 

 his note book ; the Planter wondered in vain where the drinks Avere ; the Inventor 

 reappeared from the bowels of the Motor-car which for some reason had moment- 

 arily stopped panting ; the last man stepped in and, Hey presto ! in two minutes 

 Henaratgoda was left far behind as we sped Colombo- wards. — Ceylon Observer. 



POLLARDING AND THUMB-NAIL PRUNING RUBBER TREES. 



1 



The following letters in the local press followed the publication of the 

 preceding article on " Rubber at Henaratgoda, Ceylon :" — 



Neboda, Jan. 15th, 1906. 



Dear Sib,— Your article under the heading " Rubber at Henaratgoda" in the 

 Ceylon Observer of January 9th, I read with much interest. I would like to make 

 a few criticisms thereon from knowledge gained by practical experience. 



Pollarding. — What would be the result from pollarding was in my mind 

 in 1904 when I tapped two 10—12 year old trees at about 15 feet from the ground. 

 Both trees were healthy and freely yielding latex. The ultimate result has been 

 the same in both cases, so that I shall only deal with one, No. 596, pollarded 11/3/04, 

 and measuring at 3 ft. from the ground 34 in. in girth. For the purpose of com- 

 parison I must include another tree standing some 12 ft. off, No. 597, measured the 

 same date, girth 31 in. — not pollarded or in any way interfered with. Since No. 596 

 was pollarded several attempts have been made to extract latex with unsatisfactory 

 results. In fact, I may say, 596 has given no latex from that day to this. (It 

 looks as if it might be induced to give us a little now, and we are making another 

 attempt.) Both trees have been tapped with the V knife in 1903, and their skins 

 at the time the experiment was commenced Avere fairly thin. No. 597 (not 

 pollarded) Avas tapped three times in 1904 and every other day for the best part of 

 1905, and is still being tapped. The bark is thick, milk flows freely, and the tree 

 is in every way healthy. 



