April i, 1886.] THE TROPICAL AGRICULTURIST. 



681 



EXTRAUTIXG VEGETABLE OILS. 



Here where the castor oii tree grows like u weed 

 auJ is ptreuaial, and where the ground-nnt grows 

 freely, to say nothing of the olive and other pro- 

 ducing fruits nud plants, the following nccuont from 

 the S. A. Adrti'tiser of n new machine for extracting 

 oil invented by a South Australian citizen will be read 

 with interest. Our contemporary says : — It has been 

 found that the usual system of pressing the seeds to 

 obtain the oil contained in them is much too expens- 

 ive to be succesfully carried out in a country where 

 labour is so dear as it is in Australia ; and Mr Birn- 

 baum, who has studied the subject for many years, 

 both practically and in the works of the best Carman 

 authorities, has turned his attention to discovering a 

 method which will minimise the attendant expenses. 

 Very briefly described, his vtodvsoperandi is as follows: — 

 The seed of the rape, linseed, or castor plants hav- 

 ing been crushed, is passed through an api>aratns which 

 looks somewhnt complicated to the uuprofessional eye, 

 consisting of a number of large zinc jars and tubes. 

 In these the oil is extracted from the seeds by the 

 use of bisulphide of gasoline, from the unpleasant 

 odour of which the oil is afterwards freed by the 

 action of heat. Still later the oil is separated from 

 the water and filtered, and ultimately an article is 

 produced which appears remarkably pure when ex- 

 amined under the microscope. The refuse which re- 

 mains after the oil has been extracted is made into 

 rape cake, linseed cake, and other articles. To manu- 

 facture sandal oil i which is well-known on account of 

 its important mciicinal properties, and is also used in 

 making perfumes), the wood is crushed by machinery, 

 nud the result is treated in the same way as the 

 seeds abovemeutioned. The sandalwood which Jlr. 

 Birnbaum uses is imported from AVestern Australia, 

 and the root gives the best oil, but it would be worth 

 while finding out whether South Australian trees which 

 bear the same name and are very odoriferous, would 

 not answer. One advantage which the inventor claims 

 for this system is that the seeds can bo used just 

 as they are clipped in bunches from the plint, with- 

 out any trouble and consequent expense being incurred 

 in cleaning them, a preliminary which is necessary 

 when the oil is to be extracted by i)ressure, Mr. 

 Birnbaum has secured a patent for tho principle on 

 which hisapparatus is constructed.— Planter and Farmer. 



STATISTICS OF PLANTS jVS (CLASSIFIED 

 ACOOKDING TO THEIR OULTUR^VL 

 KEQUIREMEXTS. 

 If we classify plants accurdiug to the garden treat- 

 ment they require they fall into four main groups. 

 The intertropical zone includes a land area of 40,000,000 

 square miles, and the total number of characteristically 

 tropical plants known to science m.iy be roughly 

 estimated at 40,000 or 50,000. These are provided for 

 at Kew in the I'alm-house, the tropical Fern-house. 

 the Aroid-house near the main gates, the central por- 

 tion of the new range, and various small propagating 

 bouses which are not opened to the public. Of course 

 the expense iucnrred in cultivating in the English 

 climate any plant of this group is considerable, so that 

 a careful selection from the 40,000 or .50,000 species 

 has to be made. The second group of plants consists 

 of those that can bear the English summer, but need 

 protection during winter. These are provided for at 

 Kew in the tcmper-ate-house, the succulent-house, the 

 cool Fem-house. and the cooler parts of the new range. 

 To this group belong the members of the three rich 

 floras of the south temperate zone, where the height 

 of summer cnrres[,onds with the depth of our north 

 temperate winter. To this group belong about 30,000 

 Bpeces, or about a third of the known plants. Next 

 come the hardy plantfi. The north temperate zone 

 occupies about one-third ol the earth's surface, and 

 its plants number 20,00" species. Of these at Kew 

 the classified collection of the herbiiccous types is con- 

 tained in what is called the herbaceous grouud, which 

 is situated north of the Cumberland Gate. Here are 

 groffu about 2,000 pereoaiaU and 1,000 ananali), 



arr.int'ed under their natural orders. The classified 

 eullectiou of shrubs and trees is scattered over the 

 different parts of what was formerly called the pleasure 

 ground. For the special growth of alpine plants two 

 rockeries have lately been laiil out. The total flora of 

 the artic zone does not reach 1,000 species, and the 

 plants which are couQucd to the higher levels of the 

 mouLtains of tlie north temperate zone may po3:;il>ly ha 

 twice as numerous, in all 3,000 species, of what garden- 

 ers call "alpines," it?., plants specially adapted to a 

 cold, damp climate, with a short summer, if we at- 

 tempt to classify the plants of the British possessions 

 under these four climate groups, tho results will be 

 something like this: — 



Tropical plants 

 Half-hardy 

 Hardy 

 Alpines 



— Gardeners' Chronicle. 



18,000 species 

 18.00(1 „ 

 8,000 „ 

 2,000 „ 



46,000 „ 



FIELU EXPERIMENTS AT ROTHAMSTED.* 



Perhaps the chief interest in the experiments upon 

 crop cultivation will still centre around wheat. Broad- 

 balk field, on the Rothamsted estate, is unique, so 

 far as treatment and cropping goes. lu Xti'i'i, this 

 lield cai'fied a crop of tm-uips, manured with farm- 

 yard dung; in 1840 it was barley; in 1841, p"as; m 

 1842, wheat; in 1S43, oats; all the foUi last crops 

 being unmauured. The field was, theref'ire, nceording 

 to all farming rules, in an exhausted state w'leu 

 the first experimental crop of wheat occupied it in 

 1»84. Every year since 1843 has this fie'd curried 

 wheat, auil with, some exceptions, nearly the same 

 description of manure has been applied to each plot. 

 In this field the visitor, during the present -''lu'mer, 

 will see the forty-second wheat-crop growing with- 

 out manure of any description upon the ninnanured 

 portion of the field, still keeping up a wonderfully 

 uaiform yield o[ about thirteen bunhels per ace-; 

 or about the average yield of wheat-lands in tho 

 United States of America. This is a striking fact 

 for those who fear the eventual exh: nstioii of our 

 soils. Equally startling is the result fr.'m tlio con- 

 tinued use of nitrate of soda year after year. This 

 fertiliser is looked upon by many landlords and 

 agents with suspicion as a stimulator and exli-uister 

 of the soil ; and yet after forty-one years application 

 of nitrate of soda, and nothing else, we have tho 

 astounding result of an average of 'I'S}, bushels per 

 acre, or double the yield of the nnmanured plot. 

 And, although it is true that the yield of 'he uu- 

 manured and nitrate of soda plots i.s leas upon an 

 average from 18li8 to 188.'! than it was fro;n l.loni 

 to ISiiT, yet it i.s equally true of the plot m-.nured 

 with 14 tons of farmyard rnaniiro anuually ; and ibis 

 falling off is therefore probably due to a succession 

 of bad seasons, more than to any actual eshau-<'i(tii 

 of the soil. Another striking fact bron^iht out in 

 these experiments is thr excellent results achieved 

 by application.s of artificial fertilisers as contrasted 

 with those obt:iined frem farm-yard manure. In 'he 

 latter case, where 14 tons of dung have been annually 

 applied to the wheat-plot for forty years in succession, 

 the very satisfactory yield of '.W. bu.shrls per acre 

 has been obtained over the entire period. When, 

 howe.ver, a well-coinpoimded mixture of artificial 

 fertilisei'S has been applied, a larger yield has 1 een 

 obtidned. For example, JOO lb. of sulphate of po'ash, 

 100 lb. of sulphate ol soda, lOO lb. of sulphate of 

 magnesia, :i?.- cwt of superphosjihatf!, and (iUO lb. of 

 ammonia salts, have given upon an averag'f over the 

 same long perioil 36 bushels per aero year by year. 

 W'f must not draw these remarks to a conclusion 

 without at least noting the interesting (xpcrimonts 



*" Memoranda of the Field Experimnds coudiicted 

 ou the Farm .aud in the Laboratory of Sir .lohn 

 Bmnett Liwes, Bart,, at Botbamsl d, Heit-i., .Tune, 

 1564." 



