Mar. , I 9 1 3 T H E -70 URSA L OF IMD USTRIAL AiVD EIVGIIVEERIiVG CHEMISTRY 2 5 5

proposition individually. The course to be adopted should charges, is below~$o.ooq. A very suitable use for coke-oven vary with the local conditions, such as the price of fuel, the gas is in heating reverberatory furnaces and steel furnaces: quantity of coke passed through the blast-furnace, and with blast-furnace gas is hardly suitable for such purposes, although the amount of power which can be used in the works themselves it is being tried in Germany.

which afford a field for the use of gases now wasted, in addition to what can be sold to other undertakings. When coke-oven gas is available, as well as that from blast-furnaces, the possible methods of utilization are largely increased. The adoption of rcgeneratib7e heating has greatly reduced the quantity of gas ivhich it isrnecessary to consume in the ovens themselves, so that fully j o per cent. of the total gases liberated are disposable for other purposes.

I n the case: of the existing French works, Gouvy considers that the PrOFam to be adopted must be largely gok’erned by the character of the present steam plant, which i t is not always fillancially possible to modernize. IVhen, on the other hand, new works are being laid out, i t is generally feasible to arrange the power plant so that i t is operated by the waste gases entirely. I t should, in such a case. be possible to operate by the waste gases the bloxving-engines, the electric power station of the works, and the rolling mills. If coke-oven gas is also available, i t should,

the steel furnaces, and the other accessory heating plant. The first essential to good results with blast-furnace gas is

to clean it, so that, as used, it does not contain than o.5 grain of dust per cubic meter. This greatly increases the evapora- taken from Engineera% 67p No’ I ’ I h :

t i vv poLver o[ any boiler heated \yith the gas, Thus, with the uncleaned gas, about 2 cubic meters are required per kilogram o f water evaporated, as comparcd with only I to 1 . 2 cubic meters per kilogram Jvith the uncleaned gas. The p e a t effect of clean- ing on the evaporative efficiency is due to the fact that the dust is an excellent non-conductor, and, if present, is deposited upon the heating surfaces, greatly impeding the transmission of heat across them to the water. In a Westphalian works, where the cleaning plant reduces the dust content to less than 0 . 2 5 gram per crtbic meter, the consumption of gas is only 0.8 cubic meter 1)er kilogram of steam superheated to 250° C.

’The Same considerations are applicable to blast-heating stoves, o l ~ ,,.hich the dust deposit has a very prejudicial Its presence impedes the transfer of heat from the bricks to the gases, and vice Tersa, and at the Same time, if a very hot blast is used, it acts as a flux, making the bricks waste rapidly, Cowper stoves, as usually worked, require from 50 to 60 per cent. of the

cleaned, the consumption for the Same blast temperature will

and by their subsidiaries, .as mines, cement works, etc., all of -~ ABUSES IN WATER FILTRATION

G , H, Pratt, at the last meeting of t,he N ~ ~ \ ~ i;rlgland \vater- Association, said that the SUCCeSS a Jyater filtration

plant depends, first, upon the selection of the method or puri- fication best suited to local conditions; second, upon the proper operation of the works after installation. slO,\. salld liltratiull for a water high in algae is not to be recollllnclldcd, I , ~ ~ . ~ ~ ~ ~ ~ ,,I the undue clogging of the beds, but by the use of acrutioii arid prefilters conditions may be greatly in1pr(,veti. I’laill filtration should not be depended upon to treat a \cry highly colored water; and the rates of filtration should nut 1)c c11a11gt.cl quickly, for such a practife tends to disturb the bacterial CLctioil at the surface of the bed. A slow sand filtratioll \\.]licl, would handle a given water satisfactorily might, as at providence, R. I., be installed without covering the beds, In the case of rapid sand filters supervisioll must i)e particlilarly close, and constant chemical control must be maintained,

THE COST OF HYPOCHLORITE DISINFECTION

The following data relating to hypochloritc tlisinfecti~~n is

Commercial bleaching powder packed in sealed drunis Iioldiiig 7 0 0 to 800 Pounds each, with a guaranteed strength Of ,36 11) 38 per cent. of available chlorine, may be purchased ill carload lots for about $0.0125 per pound. -%ssuming a disinfectaiit containing 33‘/a Per cent. of available chlorine a t a cost of $0.02 Per Pound, the treatment of a selvage with 0.1 Part per I0O,ooO available chlorine would require 2 j pounds of disiu- fectant at a Cost for chemicals of $0.50 per million gallons. To produce complete sterilization, the cost \vould be well over $1 9.00 Per million gallons for sewages and the d%ents from contact and trickling filters, and would vary from $1.50 to over $19.00

qLlalit?. which would conform to the drinking water or roo-Io-j stand- ard, the cost would Vary from 83.75 to over $19.00 per d l l iou gallons for raw sewage and effluents from trickling filters, froill $7.50 to Over $19.00 Per million gallons for settled sewage, fro111 $15.00 to $19.00 per million gallons for strained sewage and COW

and would vary between $1.75 and $9.50 per million gallons for

the

moreover, be possible to work thus the reheating furnaces, ~-~ ~

for effluents from sand filters. To produce a

whole of the furnace gases available, while if these gases are tact effluents, be Over S19’Oo for septic sewage,

be about only 40 per cent, of the total supply, Since, however, the gas is cooled in the cleaning process, special burners must

the effluents from sand ‘Iters which Were not originally of that quality. To produce a quality to correspond to

lIe provided to insure its ignition, The cost of cleaning to the limit stated should not exceed go,ooI46 per I,ooo cubic feet.

engine-running the gas should be further purified, so as to I,ring its dust content below, as a maximum, o,03 gram per cubic meter. To purify the gas sufficiently for use in gas- engines involves an additional outlay over and above the cost of the preliminary cleaning of So.oor 24 per I ,000 cubic feet. THE PAPER INDUSTRY O F JAPAN

Where coke-oven gas is available, still further economies Pafier (January I , 1913, p. 2 5 ) states that after cotton-spitlninji, can be effected. The by-products alone are worth from &.20 the manufacture of paper is the most important industry ( I [

to *%.30 per ton of coal coked. If the ovens are fitted with re- Japan. generators, about 50 per cent. of the total volume of the gas As raw material, the so-called paper mulberry bush (Kodzu). evolved is available for use elseivhere. This volume varies Broussonetia fiapyrqera (mitsumata), serves. While the manrr- with the quality of the coal from 2 jo cubic meters up to 330 facture of domestic paper is very old, the production of ‘‘ €Sur(>- cubic meters per ton coked, and i ts calorific value ranges from pean” paper was first commenced by the Oji paper mill, workin: 3,500 calories up to j,soo calories per cubic meter. The coke- with rice-straw, rags and old paper. ovens a t Heinitz, in the basin of the Saar, consume joo tons After the Saigon uprising in 18 j j , as a result of the establibli- (Jf coal daily. IVith the lvaste gases a central station of ro,jm ment of numerous printing plants, the demand for ISuropeali horse-power is operated and power is furnished to the surround- paper increased enormously. The manufacture of doniestic ing district. The price realized a t the switchboard is $0.01 per paper, mostly conducted with hand apparatus, is carried o n kilowatt-hour, and the cost of generation, including capital principally by the rural population as a secondary occupatioii,

I000-IoO-50 standard, or*one which would be about equal t u that of the better class of st.-eams not seriously polluted, the coqt would be from $1.75 to $5.60 per million gallons fur ra\v sewage. These cost estimates are for chemical only, and do not inclu~lt. Operating and sinking fund charges*