-ilAV_lL.l'.»ll.> 



_The Weekly Florists' Review* 



21 



^vitli IIki liydrocyjiiiic acid ^^as as fast 

 ,s it forincd, tlicrc iiiij^ht be little or 

 iioiic of llic j^Ms left to do its work. 

 llMTrrorc. use a practically pure potas- 

 iiiMi cyanide. 



The Sulphuric Acid. 



I'liliajis tlic siil|ilniric acid is tli(> 

 lid.^t \arial)lc of the tlirc(> factors used 

 ;ii liiini^at idii. At least, it: is exceed 

 ii^lv iiripiirtant that it should meet 

 ,it;iin re(|nireiiieMts it' the treatment 

 ,. |() he satisfactory, as t lu> use of a 

 akiiil; .urade of a<'id is liable to cause 

 ijiiiy to f(dia.i;e. ( 'oinmeicial suli)huric 

 ,, id is sat islacf ury, ]>rovide(l it coii- 

 jiiis no nitiic acid and is of the 

 iieii,^;tli known as (id deurees Hauuu''. 

 ~;i(h an acid should ,a\era^(\ ninety- 

 luce to ninety lour per cent of actual 

 il|ilniii<- acid, tlie idher six or seven 

 I I ( ml consist ini; of impurities of 

 iiiiMis kinds. Sulphuric acid is made 

 illiei I'roMi free snlphur or from sul 

 hur coiuliini'd with iion or' ('opj)er and 

 iiowii as ]iyrilcs. Ordiiuirily the pv 

 Mcs u:^e(l ciintains ;ii'senic, etc., to 

 nine I xteiit. In the u:a nnl'.act ure it he 

 .iin( s iiii.xed with I'liines (d' niti'ic acid 

 in. I. when ])yiites is Ui;ed_ r.ather than 

 idplinr, 7nnch more nitric acid becomes 

 i:i\ed with lh(> sulphuiic acid produc(Ml 

 ili.m in the case where sulphur is 

 ■alwn. Tin' nitric acid can be removed 

 h\- r(diuinii'. (d' coiiise, but this in- 

 . lipases t he cost . 



'The danii'er in IiaNin^- niti'ic acid 

 jiicscTit is that it is energetic iu its 

 irtion :ind also xolatili/.es i-e.adily. .\c- 

 ordini^ly, when sulphuric acid coutaiu 

 iii.u il is added to water, the heat pro 

 liiced be;;iiis lo \(datili/e the nitric 

 •icid, ;ind wIkmi the cyanide is added it 

 iiicre.ises tli<> lu^at, ;ind the jiassinj^ oil' 

 into .lir of the hydi'ocyaTiic acid f,'as 

 auscs the nitric acid also to pass into 

 the .lir. \\lien this coiid(>nses aj^ain on 

 ilu' le.aves its action is vigorous and 

 ilsu extremely injurious, causinf,' bnrn- 

 \UiS wherever it touches. 



l'"or the jrieatest ei'onomy of j^'as ])ro 

 dnction, tha»r<lje acid should be of the 



Prof. Henry T. Fernald. 



i^r.'ide kruAvn as (TtV de^r,-o,.v5 J{aume, and 

 111 adijition it shoimb T>«' rntirelv free 

 rrcuii nitric acid. J 



Proportions of the Ingredients. 



or the water little need be said. It 

 IS. wf course. ])ossible that waters con- 

 laininir impurities mi;:ht include some- 

 'hin;i which could modify the chemical 

 lidccss to sonn' extent, but this, at 

 least in >sew lliii/land, would in all 

 probability never be the case. 



'I'he proportions to use of these dif- 

 ferent nuiterials have been variouslv 

 -iven at different times. Oiu' writer, 

 who has been wid(dy IOIIowinI, says: 

 " •\ half more acid, liquid measure- 

 'iient. than cyanide, and a half more 

 ^\!it(M- than acid are used." Another 

 •^ui:-:,.sts a li: :'. ■ formula. h'ecent 

 -tudies on this jioint have been based 

 "II the )u-inciid(> that when one chemi- 

 ■il acts upon another to ]iroduce a 

 'kinl, the amount actu.ally used is al- 

 ^^•■lys the same, and the presence of 

 ""lie than enough of either simply 

 ''"'■■Ills :i suiplns of it hd't unchani:ed 

 If the comjdetion of the combination. 



I lie actual pi'ocess of combination of 

 (he chemicals is expressed as follows: 



'-'KIN -1 n„S(>^ - - K„S(), + SIICN. 

 , I '.'iMKsiiiin cN.iMidc ;- livdiMycii siil|iliat(' r^ po- 

 ■■i"^iMiii siilpliiil.' . liyilr,ir.\;nii.' nci.l. 



An Excess of Acid. 



'i we take :in ounce by weight of 

 ^'"^ pidassium cvanide. we find that 



three cpi.arters (d' .a tliiid ounce ot' sul 

 phiiric acid is snilicient to uivc hydio 

 ^^(Mi enouj^h to conddtu' with all the 

 cyano;i:en there is in tin' potassium cy 

 .nnide. ( >n the other hand, a little of 

 the hydrocyanic acid may dissoKc in 

 ■ the water jiicsent instead of ]iassinj^ 

 I off into the aii- as a j;as, ainl wouM 

 thus be lost, so far as use ^oes. The 

 addition of another i|uarter of an 

 ounci^ of acid will heat the water more, 

 and tend to drive the ^as out, so that 

 for this I'eason^ it seems to ])ay to use 

 a little excess of acid o\('r what is 

 needed for the chemical jirocess, to ;ret 

 more of the j^as. 



Too much excess of acid. howe\ cr, 

 produces trouble in a difl'(>rent way. 

 The formula j:i\en shows that potas- 

 sium sulphate is formed in addition to 

 the hvdrocyanic acid j:ns. Now. jiotas 

 sium snl|diate, thou^iha s(did, dissolves 

 j in the water ]ii-esent. but if there is 

 I inuch spaie sul|dinric acid also presi^nt, 

 less (d' the potassium sulphate dis 

 sohes, and insteail it tenijs to form ,i 

 crust co\ciiii^ the jiieces ot' |iotassiuni 

 1 cvanide not already acted upon, so 

 1 that the sididiuric acid cannot le.ich 

 j these jdeces to combine with them and 

 1 produce more ^as. for this reason 

 then, too niindi acid is as undesirabli' 

 as too little, .and it after ;i t'uniiLi.at ion 

 has been conipleteil there is a solid or 

 a slushy substance left in the dish, this 

 indicates that either too little watei' or 

 too much aiid was used. 



The Action of the 'Water. 



.\t present, then, tln^ proper amounts 

 to use seiMii to be: < )ne ]part by weii;ht 

 of cv.anide. aini one part by nieasui'e ot 

 .acid. 



Wat(M- is not abscduteiv (>ssenti;il to 



the ]irodn(dion id' hydrocyanic acid "as 

 by tin- action (d' sulphuric acid on j)0- 

 tassiiim cyanide, as the acid could be 

 jioured directly upon the cv.anide, and 

 souM' iras be j:i\('ii oil'. 'I'he ])rf)ees9 

 woidd ipiiidtly come to ,an end, how- 

 e\('r, in this case, as the pot:issium sul- 

 phate formeil would so coat o\'er the 

 cyanide that the acid would either fail 

 to ri-ach it or would do its work too 

 slowly. Water is useful in dissolving 

 both the cyanide and tlie pot.assium 

 >-ulphate produced, aiiil in hastening 

 the (luMuical reaction, which is of im- 

 portance, ;is tJu' maximum .amount of 

 yas is needed as (piiidvly .as yuissible for 

 (dfective results. If too little water is 

 present the jKdassium sulphate tending 

 to coat the cyanicle is not dissolved, 

 and this delays the juocess it" it does 

 not in p.ivt jirevent it. 'I'heu the heat 

 I'ro.luced by mixinir the acid and the 

 water is a lire.at ad\ ;int,a;:e, ;is it has- 

 tens the chemical I'eaction. 



It is evident that too litti.' water 

 will prevent the ]iroduction of the 

 iiia\iinum amount ot' uas. Ivxperiment 

 shows that too much wat^r acts in the 

 same way. more ot' the ^.-is (Mitering 

 the w.-tler and thus r.-duciuL'' the 

 amonnt in the ;iir. A series of tests 

 usinij- \;ir\inL:' aiiionnts di' w.ater has 

 ■<hown that for the be-t results there 

 -^houbl be three times as much \vatiT as 

 •■•'•ill, and the best proportions of all 

 three materials to \i>e, thtM-(d'ore, be 

 come: 



t'.\ :niic|.\ iiiH' p:iii l.y « . i-ht. 



.\lill. line pjll hy llii';l^llli'. 



W:ili-i. llinc ii.irt^ l.y iii. ;i~iir,' 



The Right Order in Mixing. 



It is .joirable to utilize tlie heat pro- 

 dii<-e.| liy th.' a.l.jition ot' the sulphuric 



