5S4 



THE TROPICAL AGRICULTURIST. 



[January i, 1883. 



not very far from Asuncion — the process being a simple 

 one, without previous maceration. Should this invention 

 prove a success (autl I am promised further particulars 

 from the persons undertaking this work), the " caraguata " 

 fibre will become an extremely important article of export, 

 and if half I hear of it be true, should compete with 

 advantage against jute. — Frodnce Markets' Iteview. 



OARBOLIO AOID AND WEEDS. 



The following report is from the Royal Botanic Society's 

 Quarterly Kecord, which describes some experiments in 

 destroying weeds on gravel walks : — " As requested by the 

 committee, I have to report that since my experiments 

 in ISOii) with chemical compounds, with a view to deter- 

 mine their relative values in the destruction of vegetable 

 growth uii gravel walks, additional trials have from time 

 to time been made with a variety of substances recommended 

 for the pui'pose — amongst others, sulphuric, sulphurous, 

 hydi'ochloric, and carbolic acids, chloride of sodium, sulphate 

 of copper, chloride of zinc, tlowers of sulphur, jjaraffin 

 oil, and Burnett's and other disinfecting fluids; and also 

 during 1870-1877 a large quantity of refuse fluid ; presented 

 to the society from a colour-works, which contained free 

 sulphm'ic and other acids, sulphate of copper, and most 

 probably other metallic salts. It was used in the propor- 

 tion of one of mixture to three of water, and its application 

 destroyed all vegetable growth, and none reappeared on 

 the walks for more than three years after. Since 1877, 

 however, we have not been able to obtain a fm'ther supply 

 of this or any similar liquid from any source, and the 

 authorities at gas-works report that the only refuse they 

 can supply at a low rate is .spent lime. 



" Of the several agents tried from time to time three 

 only have been retained for further experiment, aU the 

 others being considered unsuitable, either from their high 

 cost or inefficiency. These three are : — 

 No. 1. — Sulphuric acid. 

 No. 2. — Carbolic acid. 

 No. 3. — Chloride of sodium (common salt). 



" After trial of several proportions, the following were 

 determined upon. It will be noted that the proportion of 

 sulphm'ic acid is given by weight, as this is, for weU-known 

 chemical reasons, the most rehable measure ; the weight 

 of salt is when dry as iu orthnary domestic use". The 

 relative values are based on the following commercial values 

 — viz.. Sulphuric acid. Id. per lb.; carbohc acid (Calvert's 

 No. 5) at 3s. yd. per gallon ; common salt at 40s. per ton ; 

 water cost, nil ; weight, 10 lb.=l gallon. 



No. 1. Sulphm'ic acid 1 to 15=10 lb. to 150 lb. water=10d. 

 —850 to 1,000 ft. 



No. 2 Carbolic acid 1 to 50^2Jpts. to 125pts. water=14d. 

 —850 to 1,000 ft. 



No. 3. Salt, bti lb., 12d.— 850 ft. 



" The area of walk treated with each amount of liquid 

 is stated at from 860 to 1,000 superficial feet, as the quantity 

 required depends upon the torm, pitch, or condition of 

 the walk — such as rough, damp, shaded, i:c., and especially, 

 in relation to sulphuric acid and salt, both of which have 

 so high an afiinity for water that the hygrometric condition 

 of the i^ravel is important. 



" The action of the .several compounds is as follows : — 

 No. 1, sulphuric acid, is immediately fatal to all vegetation 

 on contact. No. 2, carbolic acid, is slow in action, gradu- 

 ally tmrning the leaves, and especially the roots, hay- 

 brown. No. 3, salt, is almost immediately fatal on a damp 

 walk, or after the first wet day, and in a short time a 

 few sharp showers of rain wash the gravel clean and 

 bright. 



"The preventive action of salt is only good for about 

 three or foiu: months, vegetation reappearing in perhaps 

 an aggravated amount on damp or shaded walks. As yet 

 the duration of the preveutive action of the acids has 

 not been fidly determined, but the garden superintendent 

 has marked on a plan the walks as severally treated, 

 and the fellows of the society and risitors to the garden 

 will be enabled to judge the relative values of the agents. 



" The liquid compounds were spread over the walk by 

 the ordinary water pots with tin roses. Lead or pewter 

 would be better, zinc must not be used. A rose made of 

 thin sheet German silver resisted the action of the sulphuric 

 acid weU. 



" For the distribution of the salt I constructed a special 

 machine. It consists of a square box sieve of perforated 

 zinc mounted on wheels with an automatic action, so 

 arranged as to communicate to the sieve a jolting motion 

 when drawn along the walk. 



" The weeds ou the walks consisted of grass, spergula, 

 and small varieties of moss, &c. 



" From time to time I will report the result of the 

 experiments, and shall be happy to make trial of any 

 other agents recommended. — W. Soweeby, Secretary." — 

 AustraUtaian. 



THE TREATMENT OF CHINA GRASS. 



China grass and other fibre producing plants are generally 

 cultivated at loug distances from the localities where the 

 fibre is prepared for the market. The plants are cut 

 down and tran.sported across the country to the scutching 

 mills. This gave rise to two evils: in the first place, 

 about a ton of raw, woody material is transported to pro- 

 duce 1| cwt. of fibre ; and, in the second, the gum in the 

 grass becomes dried up during transport and the separation 

 of the fibre from the wood and epidermis is rendered 

 both difficult and expensive. In order to remedy these 

 defects and to cheapen the production of fibre generally, 

 a simple and inexpensive process has been devised by 

 M. Favier, and is being introduced in England by Messrs. 

 Brogden & Co., of 4(JA King AVilliam Street, London. This 

 process consists in steaming the fibre-producing plants at 

 the place of culture and senchng only the epidermis with 

 the fibre attached to it across country to the mills. The 

 process was shown iu operation lately at the works of 

 Messrs. Middleton & Co., iu Southwark, and was witnessed 

 by General Hyde, of the India Office, and a number of 

 other gentlemen interested either in the production or 

 use of the fibre. The apparatus employed is very simple 

 and inexpensive, consisting merely of a stout deal box or 

 trough, 8 feet long by 2 feet wide and I'O inches deep. 

 This box has a false bottom, under wliich runs a |-inch 

 iron steam-pipe, connected with a boiler, and having perfor- 

 ations. At the bottom of the box at one end is an outlet 

 for the coudenseil water from the steam. luto this bos 

 a number of specimens of fibrous jjlants were put, including 

 two kinds of China grass, the Althea or mallow, the black 

 and white mulberry, hemp, and tlax, the samples having 

 been obtained from the botanical gardens at Kew and the 

 Jardin des Plautes at Paris. The lid having been closed, 

 steam at a low pressure was turned on, and in twenty 

 minutes the specimens were found to be in excellent con- 

 dition for stripping the epidermis ^x-ith the fibre from the 

 wood, the gum having been partially dissolved and the 

 samples properly softened. The general opinion of those 

 present was that the process as such was a perfect success. 

 It is stated that the cost of producing the fibre ready 

 for the scutching machine is only 21. per ton. The results 

 point not only to the reduction of the cost of preparing 

 the fibre in counexiou with the existing fields of its culture, 

 but in utilising vast tracts of arid waste land which are 

 available for, and adapted to, its cnltivation, but which 

 are so far removed from the mills as to be at present 

 useless. The question of fuel for raising steam docs not 

 arise, inasmuch as the wood of the plants can bo used 

 for this purpose after separation from the epidermis, if 

 no other local source of fuel exists. It is intended in 

 practice to attach a small steam-producer to each of the 

 steaming boxes, and to employ juvenile labour largely in 

 the process. The matter is of interest to our Colonies, 

 and. other things being equal, M. Favier's invention will 

 doubtless prove of great value in connexion with the fibre 

 trade generally. — Colonies and India. 



METHOD OF DESTROYING WASPS. 



TO THE EDITOE OF " INDIAN FORESTER." 



Sir, — Have any of your readers heard of, or tried, the 

 following method of getting rid of wasps' nests in the 

 verandah':^ It was told me by an old police inspector; 

 but as I am now living in a country M'here wasps are 

 not. I have never tried it. Get a china basin, clear it 

 thoroughly, place some sugar, treacle or any sweet stuff 

 in it, then lead a stick to serve as a ramp from the 

 basin to a black ants' nest (the big square-headed fellows 



