Arizona citizen., 1875-10-23

. Oi t.l- tt C}ui ilstl ihtutS' or tue lOilOM
 ing form and heated by one furnace
 The bottom of each measure flom ih. bridge, leng;hwise 3.l0 mc.-.s. ani tht
 width from lhe mouth. measures 3G-
 me:rts The yauh, which a; ,he place
 where the fire enters. has a heighI
 above the floor of 0jS mcircs and zoe.
 slar;iag downward towards the fiue
 whe:c il has only height Of 030
 The grate is from 22U ;o 2.50 metre.
 long, and from 0S0 to 0.;i5 metre. wide
 the distance between tl. bars beina 90l5, in order to admit he air; the
 thIek!Ws4 cl the baf~ , liula more
 than 0.0ij, 80 that the surlace of the
 entering air would make a square,
 whose side would be about 0.GO metres
 the bridge which separates the floor
 from the hearth, is only 02s metres
 wide, by 0.2 metres high. the section
 of the chimney should mol sarpass a
 square having for side O.4J to 0.50
 metres: its height varies between four and six metres.
 The floor of the second furnace or compartment, should be about G.I me. tre higher than that of the rirsi, the same takes place with regard to the third, which communicates with the chimney.
 The communication of one hearth with the other has nearly the same width as inc fireplace; only the com munica,ion of the third with the chim- ney is reduced t1 ;he iue of the 1bIm- ncy or is made t0 communicate with f by three different conducts: the com municauon of one hearth with the oh. er as well as that of the lasJ with the chimney, is arranged as indicated. in order that the flame may ba.hc equally the first hearth. and the same happens wi'n the air and the hot e,.ses of the others The greater heighto o. fhc arch OF vault near the fireplace and tha, ador.ed for the outlet cause the flame to extend itself over the whole hearth. passing four or five centimaues above the ore, making iu this manlcr i,s ac- lion more oXidizinc; for it is well
 known that when jhe combustion i- no; perfect the gases forming tha flame have 8 reducing ac.iontba. :aiGrcs ,h, going on of ihJr4a,.iHg. tbi1r which aoe. uo: happen yi,a Cie saum of uot ai- Jha. in.erposc- it.nlf between ihc 1amAnd the Ore and .hc action ui which is always ozi3izing.
 These furnaces a.c charged win 36s Kilograms abou, 500 pouad..J which charge it seems 70 me. should not cx- cead 3J0 Kilograms. in order that ,he layer of ore might be les thick. ior lhe easier the operator can sir i., tb- more complete would be the action of the hot air upon all the o-c. | have charged furnaces of those dimensions with 23O kilograms otbout 50O pounds) and have obtained sufficiently satisfac- tory results
 Of the manner of charging and dis charging the furnaces, of the rakes, shovcls, etc, which are used, I shall not speak. because between those oper- ations and utensils and those described in ;he trcatises about working of ores, there does not exist any essential differ cnce; I shall, however, speak of the manner of conducting the roasting, which is not at all equal to that used in the working of ores by the barrel process.
 In order to commence the operation, first the bearths are heated, for which purpose the damper (slide) is closed, which for that purpose is on the chim- ney, also the doors. and the furnace is charged and lighted, generally at the end of six hours the furnace is hot The charge is placed in the third com partment, which as I said before, is that nearest the chimney; the operator extends it well over the whole floor, using either the shovel or the rake. Once extended he leaves it without stirring that it may become warm, and at the end of half an hour he begins to stir it with the rake (h0e) in order to facilitate the escaping of humidity and uniform heating of the ore; some sulphur commences to escape; two hours after the charge was made, it is moved 10 the following or second hearth, which the operator performs with the shovel; on this hearth the heat is greater, the eXhalation of sul- phur stronger and the oxidation of it which converts it in sulphuric acid, becomes another source of heat, which united with that from the hearth, ele- yates the temperature of the ore to a light red heat The escaping of the volatile substances separates the parti- ,les of the ore from one another, giv-I ng to the charge such a mobility that n very sulphurous ores the operator in moving the rake has no other resist lnce to overcome than that of moving he rakinp over the bare surface. which I