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THE TROPICAL AGRICULTURIST. 



[February i, 1883. 



USE AND ABUSE OF IVIANUEES. 



Nothing is more important in agriculture than a tliorougb 

 understanding of tlie manure questions, but at present 

 " practical men " are very imperfectly informed m that 

 department, purchasing large quantities of adulterated 

 manures (see Dr. Voelcker's evidence before the Koyal 

 Commission), and wasting money annually by their in- 

 judicious use. The waste of manure has long been a 

 characteristic failing. I remember when the most money- 

 sparing race of men in the world, clad in leather gaiters 

 and round frocks, spending almost nothing upon liLxuries 

 or conveniences, lost hundreds in the waste of manvure 

 In those days it was the farmyard dung that was wasted 

 in great open yards where the rain washed it, and rivers 

 of water ran through it from acres of untroughed build- 

 ings. Now it is the artificial manure that is wasted. 

 The shortest answer to the question, "what is manure?" 

 would be that it is the raw material of our crops, 



" Don't talk to me about Messrs. Lawes and Gilbert," 

 said a large farmer ; " if I was to dose my land with 

 nitrate of soda, I .shoidd grow nothing." He may be 

 right ; but heavy-land farmers, as a rule, swear by mtrate 

 of soda, and, as one of them expressed it, they have 

 " tickled the land " with it very much to their advant- 

 age Nitrate of soda yields one of the most costly and 

 important constituents of plant food ; but it does not 

 yield all, and is not therefore a complete manure, except 

 in the case of soils containing an inexhaustible supply of 

 the other constituents of plant food. On the chalks of 

 the North Downs nitrate of soda is not much used. The 

 soil is not rich in its natural store of mineral plant food, 

 and, if nitrogen be added in excess of the available min- 

 erals a blight or some other disaster, may be expected 

 to follow. But there is a belt of land beneath the downs 

 which is, on the contrary, well storeil with minerals, where 

 I have known the land to be skilfully "tickled" with a 

 little nitrate with excellent effect. I know one clever 

 farmer who has used in certain fields no other manure 

 than nitrate of soda for many years, and he has sold oflf 

 the whole of the produce. This gentleman farms both on 

 and under the hill, having a slice of chalk and of better 

 land below- a little fat and a little lean; and if he had 

 been a man with one idea and a prejudice against nitrate, 

 he could not have prospered as he has done.— T. Quickly. 

 —Field. 



COTTON OAKE. 



A recent number of the Annales A(/ronomii}>ics contains 

 an important article by M. A. Renouard fils entitled 

 " Etude sur les torteaux dc cotton." It appears that since 

 the year 1872 the consumption of cotton cake in France 

 has undergone a steady increase, and that it is now 

 very extensively used for cattle feeding. In 1880, the 

 amount of cotton cake imported into France was 440 

 tons and of cotton seed 21,160 tons. In the same year 

 nearly 2 700 tons of cake was exporteil by France, and 

 most of this came to England. The chief supplies both 

 of cake and of seed are derived by France from Turkey, 

 Efypt, and Italy, only a comparatively small quantity 

 arnv-ing from the United States. England, on the other 

 hand, obtains most of her cotton cake from the United 

 States, while cotton seed comes chiefly from Egypt. Mar- 

 seilles and Rouen are the leading towns at which the 

 cotton seed is crushed, and the oil so expressed is used 

 by painters, varnish makers, and soap manufacturers. But 

 it is only since the year 1860 that the extraction of the 

 oil has " been carried on on a commercial scale ; before 

 this date vast quantities of seed were allowed to accu- 

 mulate and to rot at the cotton plantations. It is an in- 

 dustrial tact of considerable interest and significance that 

 at the present time the seed is often more valuable to 

 the planter for its oil and oil cake than for its cotton 

 fibre, of which latter it contains only about one quarter 

 of its weight. , . , ^ j • 



In the United States the cotton seed is harvested in 

 the months of October and November : it is carefully 

 gathered in bv women, and then spread out to dry 

 until it is hard to the teeth. By mechanical appli- 

 ances the cotton wool is then separated from the re- 

 mainder of the seed. The later gathered seed are of 



better quality than those harvested earlier in the season ; 

 the later are found to be more watery, they are greener 

 and softer, the cotton is not so easily removed, and they 

 are liable to get crushed iu the decorticators; besides 

 these drawbacks the oil obtained from the earlier seeds 

 contains more water, mucilage, and resin, it is only clari- 

 fied with difficulty, and easly turns rancid. 



For the extraction of the oil the seeds are first screemed, 

 then crushed between fluted rollers, and afterwards ground 

 into a regular paste, which is heated in an oven in order 

 to coagulate the albumen. The whole mass is then sub- 

 jected to an enormous hydraulic pressure for a period 

 of five minutes, during which the greater part of the 

 oil is forced out. The cakes are then taken out, and, 

 after the addition of 5 per cent, of water, are crushed, 

 dried by hot steam, and again pressed, and they may 

 even be pressed a third time, the cake finally retaining 

 not more than 9 to 10 per cent, of its oil. The cakes 

 next undergo a trimming process, and are then dried 

 for about three weeks, by which time they are hard enough 

 for transport. — Adelaide Observer. 



CARBOLIC ACID AND WEEDS. 



The following report is from the Royal Botauic Society's 

 Quarterly Record, which describes some experiments in 

 destroying weeds on gravel walks. 



"As requested by the committee, I have to report 

 that since my experiments in 1869 with cheniical com- 

 pounds, with a view to determine their relative values 

 in the destruction of vegetable growths on gravel walks, 

 additional trials have from time to time been made with 

 B variety of substances recommended for the purposes — 

 amongst others, sulphuric, sulphurous, hydrochloric, and 

 carbolic acids, chloride of sodium, sulphate of copper, 

 chloride of zinc, flowers of sulphur, par.afiin oil, and 

 Burnett's and other disinfecting fluids; and also during 

 1876-7 a large quantity of refuse fluid, presented to the 

 Society from a colour works, which contained free sul- 

 phuric and other acids, sulphate of copper, and most 

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

 portion of one of mixture to three of water, aud its 

 application destroyed all vegetable growth, aud noue re- 

 appeared on the walks for more than three years after. 

 Since 1877, however, we have not been able to obtain 

 a supply of this or any similar liquid from any source, 

 and 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, all the others being 

 con.sidered unsuitable, either from their high cost or in- 

 efficiency. Those 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 de- 

 termined upon. It will be noted that the proportion of 

 sulphuric acid is given by weight, as this is, for well- 

 known chemical reasons, the most reliable measure; the 

 weight of salt is when dry as in ordinary domestic use. 

 The relative values are based on the following commerci- 

 al values, viz :— Sulphuric acid. Id. per lb. ; carbolic acid 

 (Calvert's No. 5), at 3s. 9d. per gallon; common salt, at 

 40s. per ton; water coast, nil; weight, 10 lb. = I gallon. 



No. 1. Sulphuric acid 1 to 15=10 lb. to 160 lb. water 

 =10d.— 8.10 to 1,000 ft. 



No. 2. Carbolic acid I to 50=24 pts. to 125 pts. water 

 =14d.— 850 to 1,000 ft. 



No. 3. Salt, 56 lb., 12d— 850 ft. 



The .area of walk treated with each amount of liquid 

 is stated at from 850 to 1.000 superficial feet, as the 

 quantity required depends upon the form, pitch, or con- 

 dition of the walk^such as rough, damp, shaded, &c., 

 aud especially in relation to sulphuric acid and salt, both 

 of which have so high an affinity for water that the 

 hygrometric condition of the gravel is important Ihe 

 action of the several compounds is as follows:— No. I, 

 sulphuric acid, is immediately fatal to all vegetation on 

 contract. No. 2. carbolic acid, is slow m action, graduaUy 

 turning 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 tune a few 



