coke (partially distilled coal), over which trickle.- sulphuric acid from 

 t IK- reservoir M. This arid In-. absorbed in the cud town 1 K t lie oxides of 

 nit i-o -. MI e -raping tVom t lie chamber. This end lower is also Tilled with 

 voki . over whirh a stream of strong sulphuric acid trickles from the 

 reservoir \i. The acid sjireads over the coke, and, owinv; to the lar^e 

 surface oil'ered 1 y the coke, absorbs tlie greater part of the oxides of 

 nitrogen escaping from the chambers. The sulphuric acid in passing 

 down the tower becomes saturated with the oxides of nitrogen, and 

 (lows out at A into a special receiver (in the drawing situated bv tlie 

 side i if the t'u rnaces ). froii i which it is forced up the tube.-. I, //'bv steam 

 pressure into the reservoir M, situated above the first tower. The Leases 

 passing i hroii u'li this tower from the furnace on coming into contact 

 with tlie sulphuric acid take up the oxides of nitrogen contained in it. 

 and these are thus returned to the chamber ami ai^-iin participate in the 

 reaction. The sulphuric acid left after their extraction Hows into the 

 chambers. I hus, on leaving the first coke tower the sulphurous anhy- 

 dride, air. and vapours of nitric acid and ot the oxides of nitrogen pass 

 through the upper tube /// into the chamber. J I ere they come into 

 contaci with steam introduced bv lead tubes into various parts of the 

 chamber. The reaction takes place in the presence of water, the sul- 

 phuric acid falls to the bottom of the chamber, and the same process 

 lakes place in the following chambers until the whole of the sulphurous 

 anhvdride is consumed. A somewhat greater proportion of air than is 

 strictly necessary is passed in, in order that no sulphurous anhvdride 

 should be left unaltered for want of sufficient oxygen. The presence of 

 an excess of o.xvovn is shown bv the colour of the ibises escaping from 

 the la.-,1 chamber (into I)). If they be (.if a pale colour it indicate.-- an 

 i iis.u thciencv ot air (and the presence of sulphurous anhvdride), as other- 

 \\ise peroxide ot nitrogen would be formed. A very dark colour shows 

 an excels < it air. which is also disadvantageous, because it increases the 

 inevitable loss ol nitric oxide by increasing the mass of escaping 

 Leases.'' 1 ' 



1 l'.\ ili . - a- iniicli a ~ -J.M KM iini kiliiLfraiiis dt' I'li.-iniliiT in-ill, cnm-.iinin^ uliuut 

 f,(i |..c. n] I In li\ ili-.iii- I i ,S( ), ;ii ii I ill ii nit. Id |i-r ( -i -nt . of \Viitrr, ni.i \ In- 1 1 i.i nu tart urnl 

 i . < | '!,i n: ' 1 1 r.iHin ,-ul ,,,- i uci r,.-, en | MI- it \ ' \\ ii In nit -l.i|i|M-'- -I. Tli is process 

 ii.i In i i ; In -i n -I i ,i ili-jl' 1 ' 1 ' "1 pi-l't'i-rt inli t ll;il ii- iiillrll :i - .".I 111 parts M| 1 

 r< "111 i I miii I n ! i p:irt- nl -nl pi i iir, \s hiUl t lit' I ln'iin-l i<-;i] iinn 



...".: |. . , ! Th,. anil part U itll it- r\rc-> "I Uiitrr <Hi hciil III-. 



!,M| . a, I M ,]- . II., \\c\cr. : ii.' ami >< ml a 1 1 1 i 1 1 _ alnuil 7.', per cent, of 

 ;, c,i i i',.,11111^ . aln M.|\ IH-JIII to arl mi I In- le.-nl u hen he.ite.l. ami 1 herefore 



|, ,T I . ,i in (, nr arl ..!< - ,ni -ulphurie iirnl. The ai|ll, arid (.Ml I'.allliir) 



n ,i , ,| , haiiilier ami. The ami eolieeiil rali-il to HO 



