46 



THE AGRICULTURAL NEWS. 



February 8, 1908. 



COirCENTRATED LIME JUICE AND 

 CITRATE OF LIME. 

 The following iiitorinaliuii as to methods of prepara- 

 tion of cnnceiitnileil lime juice and manufacture of 

 citrate of lime is given in continuation of the articles 

 on lime growing, etc., that appeared in recent numbers 

 of the A(iricidturul Heirs (Vol. VI, p. 41-t;and Vol. 

 VII. J.. 14):— 



CoNCENTKATKh l.LMK .H'U'i;. 



Lime juice for concentratii in :^linul(l, wlini leaving the 

 mill, be carefully strained in order to ri'ino\r all seeds, and 

 as iimcli pidp as possible before it is run into \ats. It is then 

 placed in a still, in order to obtain the oil, and afterwards 

 run to the tayches to be concentrated. It has lately been 

 fihowu ( HV.<? Iiididti lUillitiii, Vol. VIII, p. 171). that lime 

 juice, car<;fully strained and settled after distillation and 

 before concentration, has obtained a special market and 

 commands higher prices than ordinary concentrated jidee. 

 Lime juice is usually concentrated before shipment to 

 the citric acid makers in order to reduce bulk. It is usual 

 to reduce at the rate of 600 gallons of raw lime juice to 

 iJO gallons of the concentrated product. This Is concentrat- 

 ing at the rate of 12 to 1. Some estates however, concen- 

 trate 10 to 1 and others 9 to 1. Even with low concentra- 

 tion there is a considerable los.s of acid. 



The juice is shipjied to New- York or London in hogs- 

 heads of 52 gallons, where it is tested and paid for according 

 to the citric acid contents. 



Planters can novr test their own lime juice in the 

 boiling house, and thereby save a considerable destruction of 

 citric acid during concentration, by means of a citrometer or 

 an ordinary s[)ecific gravity hj-drometer. .\ description of 

 a .scale i>repared by the Hon. Francis Watts, CM. (J., D.Sc, 

 for use in ascertaining the strength of solutions of citric acid 

 and of lime juice will be found in the lIV.v/ Indiiin Bulletiii, 

 {\'ol. \', pli. 2.''>S-'.i). whilr a similar citrometer is described in 

 the d.'//-/'-»/^(o-<(/ JV»'.v (Vol. VI, p. 149). 



Care should be taken to remove as niueh nf the ini|iuri- 

 ties as [iossible, anil lime juieeshonld never be eoneentrated in 

 iron tayches. 



A carefully prepared juice, testing IdO to 10.^ oz. jier 

 gallon is a black, heavy, but not dense liijuid. When no care 

 i> taken to strain or settle ihcjuice, the product is as thick as 

 niolassesat the same degree of concentration. 



\Vhen raw juice is pre])arecl for .shipment, it shouhl be i nn 

 to the -etting vats through earthenware pijics, for it shijuld 

 ne\ei' be allowed to come in contact with any metal. 



4'lie concentration of lime jiuce is carried out in open 

 copper tayches, but it has licen .suggested that concentration 

 in c(jppcr or wooden \essels fitted with steam coils would be 

 an improvement over the present system. Now however, that 

 the manufacture of citrate of lime has been successfully under- 

 taken, it is doubtful wlu'thcr any effort will be made at 

 improvement iu the present system of concentrating juice. 

 For boiling down the juice veiT considerable quantities 

 of fuel are retpdreil, ami on estates where fuel is scarce, it has 

 been recommendeil ihal cjuick-growing si)ecies of Eucalyptus 

 might be advantageously [ilanted in odd corners of the estates. 

 Once established, they conhl be cut over every two or three 

 years, whereas native ti-ees once cut down, arc not ready for 

 cutting again under at least ten years. 



It takes from 1 .1 to 2 cords of wood,accordingto the degree 

 of concentration, to boil dou ji suthcient juice to fill a hogshead. 

 On some estates, fuel costs as much as from S to lO.'--. a cord, 



uhile on others, where w 1 is plentiful, the cost is not 



more than '^f. to I.s. Thi^ .|Ucstion of fuel, condiined with 



tlie cost of packages, and the high freight that has been paid 

 on liquid produce, is of great importance, and wdien concen- 

 trated juice is selling at normal prices, i.e , from £\i to 

 £12 10.<. per hogshead, testing 133 oz. to the gallon, this 

 industry cannot be said to be particitlarly attractive. At 

 pre.sent, jirices are high, and may remain so for some time. 



CITRATE OF LIME. 



In the manufacture of citrate of lime, the lime juice, on 

 leaving the mill, is carefully strained, then distilled to obtain 

 the oil. and afterwnrd.s, while still hot, it is run into a wooden 

 vat to lie neutralized with chalk. Before runinng into the 

 nu.xing vat. the juice should be passed through filter bags 

 ( HV.s-/ lii'liaii l'iiiili:tin,\o\.\TH, p. 167). The neutralizing 

 vats are fitted with [lerforated steam coils to keep the juice 

 hot, and to act as agitators during the time the chalk is being 

 added. 



A sutlicient (piantity of chalk is made with water 

 into a cream. The nu.xturo is poured cautiously into the 

 juice until the whole of the acid is neutralized. To detennine 

 when neutralizatii>n has Ijeen accompli.shed, samples are taken 

 from the mixing vat periodically and tested as follows : — 

 To a small (|uantityj of the mixture, some of the chalk and 

 water cream is added, and if this produces an effervescence, 

 more chalk must be added to the main quantity and further 

 tests made. This is continued until the addition of chalk to 

 a small quantity of 'juice produces no effervescence. When 

 this occurs, the revei-.se test is cariied out, viz. —a little of the 

 siqipo.sed neutralized mixture is withdrawn and heated until 

 all bubbles of gas are given off. .\ few dro[is of acid — fresh 

 lime juice will answer — are addi-d, A slight effervescence 

 will take i)lace if the requisite quantity of chalk has been 

 added, but if theie is too much chalk jircsent, a brisk 

 etf'er\escence will l^e produced. 



Buyers of citrate of lime penalize anything containing 

 nver 2 per cent, of' chalk, and, therefore, care must be taken 

 in till" neutralizing i)rocess not to add excess of the chalk. 



.\fter neutralization the citrate is allowed lo subside, and 

 the mother liquor is then run otf thiongh a tap fitted iu the 

 side of the vat. Hot water is then run in and steam turned 

 on to thoroughly wash the citrate. The citrate is washed 

 several times, and finally it is agitated and run through a lower 

 taj) into the filter bags to drain. It is then placed in a press 

 and finally conveyed to the drier, liecerit experiments by the 

 Hon. Francis Watts, C.M.(i., show that the use of centrifugals 

 is til be recommended for removing the water from citrate in 

 |i]iice nf the lu'css, and it can be ccniNcniently washed with 

 a .•-mall c|iianlity of hot water while in the centi-ifngal. Wdien 

 thoroughly dried the citrate should be placed in a room to 

 coed before being tightly [lacked in barrels, hogsheads, or 

 puncheons for export. 



Citrate of lime is twice as bulky as concentrated lime 

 juice, but it is nnt expected that freight on citrate will be 

 higher than on concentrated juice, as the .shipping companies 

 give a preference t<i the dry over the liqiud product. 



At [iresent, the greatest requirement in citrate manufac- 

 ture is a drying machine that will dry the citrate in a few- 

 hours without any loss of acid. The driers chieHy in u.se are 

 modelled after the pattern of the cacao drier described iu the 

 M'lxi luiU'tii liitlhiin, \t<\. 11, p. 173. The proces.s of 

 drying in this cla.--s of machine takes too long, and the 

 consunqition of fuel is too great for econonncal production of 

 citrate. Citrate from wddch moisture has been removed by 

 centrifugals can be dried in a much shorter time than the 

 ordinary pressed product. If centrifugals were generally 

 adopted and an improved drier brought into use, the 

 numufacture nf citrate of lime wnuld be considerably 

 simplified. 



