762 



THE TROPICAL AGRICULTURIST. 



[March i, 1883. 



that Dr. Trimen and Mr. Wall had impeached the 

 alleged volatility of the substance. A correspondent 

 of a contemporary having referred to the subject and 

 to Dr. Trimen's opinion, we submitted the question 

 for authoritative decision to Mr. A. C. Di-xon, the Science 

 Master in the Royal College. We append the letter 

 addx'essed to our contemporary : — 



" EVAP0RIZ.4TIOX OF C.A.P.P.OLIC ACID. 



" Sib, — Your editorial in yesterday's issue, and the 

 letters you publish about carbolic acid and leaf-disease, 

 lead me to state what was very precisely and 

 authoritatively told me a few days ago, viz., that 

 carbolic acid, exposed to the open air, as in Mr. 

 Storck's experiements, does not evaporate at all. The 

 water does so, and tlie carbolic aoid may also gradu- 

 ally disappear, but that it dissolves into fumes which 

 affect surrounding foliage is quite a mistake. I am 

 assured this is the result of proper chemical tests by 

 the highest authorities. This information comes to 

 me as from the Director of the Peradeniya Gardens' 

 and I think it would be well to call upon him to 

 verify it or otherwise. D. E." 



We add Mr. Dixon's remarks : — 



" Carbolic acid, alias phenol, oxybenzene, phenyl 

 liydrate, phenyl alcohol, is a crystallizable substance. 

 It melts at about 102° F. ; it boils at about 339-6° F. 

 It is a very stable substance. It undergoes very little 

 decomposition even when passed through a tube 

 heated to redness, so there is no chaiuc of much vapour 

 getting into Ceylon air from any of the processes 

 suggested for acting upon coffee leaf -disease. Most 

 sui-geons have used a 2 per cent solution of carbolic 

 acid to wash their liands and clean tlieir instruments. 

 Such a solution has been found to be almost inert 

 and a 5 per cent solution is necessary. But what is 

 the most startling fact is that carbolic acid dissolved 

 in mater or in oil proved totally inert. Koch discovered 

 that carbolip acid when dissolved in oil or in alcohol 

 had not the slightest influence on the vitality of any 

 of the micrococci or bacilli." 



It would seem, therefore, that it is difficult to 

 volatilize pure carbolic acid, and tliat to mix any 

 portion of water with the acid has the eft'ect of 

 rendering it inert ! But Mr. Storok still believes in 

 the carbolic acid cure, as witness the followuig letter 

 which has reached us : — 



To the Editor of the "Ceylon Ohserrer." 



Rewa River, Fiji, December 15th, 1882. 



Dear Sir,— Tlie report of the very qualified success 

 of my treatment of leaf-disease in Ceylon so far, has 

 not in the least discouraged me, since it could be 

 very likely readily accounted for, were I aware of all 

 the conditions of application. I do not know if I 

 have been explicit enough in all my instructions to 

 intending operators, and to supply a want which I 

 have seen expressed in your paper 1 will here lay 

 down a few rules for general guidance: — 



1. — Vessel covered in the manner previously de- 

 scribed and of 4 to 5 inches in diameter 



•2.— Vessel contains i pint of crude carbolic acid 

 sufficient for three months. 



3. — (Jn a solitary experimental acre place the vessels 

 every 4th row every 4th tree = 24 feet apart each way. 



On 2 to 3 acres the vessels should be at 5 x o 30 feet 

 apart and on 5 to 6 acres or a whole field 6x6 or 36 

 feet apart each way. 



4 — Let the experimental area be compact in shape, 

 square or nearly so, and the largtrthe better ; if oblong 

 let the long side be npliill, or with the prevailing wind. 



The vessels and the maimer of establishing theinas de- 

 scrbed in my last paper will answer every practical 

 purpose ; but the special vessel will have to be em- 

 ployed sooner or later simply because others will not 

 be obtaiuable in sufficient numbers for large operations. 



The diameter indicated is of vital importance, since 

 generation of vapor takes place in exact ration to the 

 surface of fluid in contact with the atmosphere, nor 

 conkl greater depth of acid ma,]i.e up for surface. 



Doing away with the addition of any water the crude 

 acid can be used in two ways. Firstly fill in your 

 J pint of acid, and for readier and stea^Uer evapor- 

 tion place a roll of old canvass or bagging about 1 

 inch thick (the contrivance alluded to in my last paper) 

 round inside the whole circumference of the vessel ; or 



Take about | of a pint of dry clean sand, the 

 texture of coarse dairy salt, put into the bottom of 

 the vessel, and pour in your acid until it saturates 

 and finally covers the sand with about J of an inch 

 of fluid. This charge I expect will liave to be renewed 

 once a month, but I think offers some advantages over 

 the full 3 months' charge, in that the monthly renewed 

 charges will yield a gas of more uniform strength aad 

 pungency, and that the body of sand will prevent too 

 easy spilling. Botli these applications are on the 

 principle of capillary attraction, and I would like to 

 have both tried and reported upon. 



The condi tions of rules 3 and 4 speak for themselves , 

 The smaller the area the more diffuse must be the gas 

 from the aggi-egate evaporating surface presented by 

 the acid in the vessels, and tlie reverse. Carbolic 

 acid gas is so very little higher than atmospheric air, 

 that it rises very slowly, and before doing so passes 

 over ground and through masses of foliage already 

 under the action of their own more immediate sources 

 of vapour, thus doubling and trebling the ettects of 

 it. In this manner, for instance, the trees on a hillside 

 have the benefit of nearly all the gas generated for 

 a considerable distance below them, as it keeps creep- 

 ing slowly up before it finally passes the limits 

 of the fiehl or rises into space. 



As for denying the volatility of the acid, that would 

 be like doubting the light of the sun or the heat of 

 fire, and those among your readers who have bee n in 

 the atmosphere of an area under treatment, especially 

 at night, will readily admit it. — I remain, dear sir, 

 yours very faithfully, Jacob P. Storck. 



The closing paragraph of Mr. Storck's letter is cert- 

 ainly worthy of consideration and puts the very 

 question which occurred to us. It the acid is not 

 volatile, what means the powerful odour, all smells 

 being due to particles of matter? And how does the 

 acid act as a disinfectant, if its particles do not mix 

 with and change to an innocuous compound a vitiated 

 atmosphere '! These are questions we should like to 

 have answered, on general grounds and apart from 

 the experiments which have cei taiuly not been so 

 successful as Mr. Storck and all of us hoped they would 

 be. Anotlicr puzzling point is how .Mr. Schrottky, 

 who was uothing if not a chemist (having come out 

 to Bombay to erect the first manufactory of sulphuric 

 acid in the East), pinned his faith to the volatility 

 of carbolic acid ? 



Tea Prep.*.ratiox. — A Ceylon planter writes ; — 

 " Corrcspoudfuce in the Indian Tea Gazette condemn 

 Kinmond'.s roller because it heats, the roll. This is 

 true, it does so, but I cannot find that this heating 

 affects the tea injuriously in any way: it hastens the 

 fermentation, and hence is beneficial. They do not 

 state wh rein the disadvantage of this heating lies, 

 and my experieuce is th.at it causes a rapid and even 

 fermentation, and does not affect the quality of the 

 liquor in any way. C'oarse leaf comes out flat, but fine 

 leaf is well rolled. The only fault of the machine with 

 fine leaf is that it spills too much, and raioces up the 

 "leaf that do^is spill. In two rolls of about HO lb withered 

 leaf each, IJlb. leaf was thus chopped up and spilt. In 

 one way. perhaps, it is au advantage that it won't roll 

 coarse leaf ; it enforces fine, plucking, quality as against 

 quantity. 



