44 BEPORT — 1867. 



Total sulphur. 

 ' Tons. cwt. qrs. lbs. 



These ores mixed gave 33-3 per cent, of sulpliiu- = 8 



Tlie ore calcined, the SO2 all going to the vitriol chamber, 

 yielded 22 tons calcined ore, containing 8 per cent, 

 sulphiu- = 1 lo 



The whole smelted gave of regidus 2 tons 15 cwt., contain- 

 ing 28 per cent, sulphur = 15 1 20 



Loss of sulphur in this stage 19 2 8 



The 2 tons 15 cwt. regulus was calcined, the SO^ again 

 going to the vitriol chamber, and gave 2 tons 10 cwt. con- 

 taining 9 per cent, sulphur = 4 2 20 



All which must be dissipated — loss 1 4 1 



Sulphur economized 6 15 3 



Or . 8 



Sulphur economized 84'8 per cent. 



Sulphur lost 154 per cent. 



On the Preservation of Stone. Bij John Spillee, F.C.S. 



For several years past the author has been studying the causes of the decay of 

 stone, and experimenting with such chemical reagents as appeared to oiler any 

 promise of being usefully applied as means of prevention. jVt an early stage of 

 the investigation it seemed probable that the corrosive action of sulphurous and 

 sulphuric acids in the atmosphere, resulting from the combustion of coal fuel, 

 would operate, in large towns especially, in a destructive manner upon dolomite 

 and the numerous class of limestones commonly employed in public buildings. 

 This chemical action, aided by the simultaneous attack of carbonic acid and mois- 

 ture, and in the winter season further supplemented by the disintegrating efiects 

 of frost, are conceived to furnish a sufficient explanation of all the tacts observed. 

 Dr. Angus Smith, Mr. Spence, and others having already directed attention to the 

 immense scale of production of these sulphur-acids, the author proceeded to quote 

 statistical data showing the extent or degree of pollution of the air from this cause 

 in the manufacturing districts of Lancashire. Numerous samples of dolomite, 

 Caen, Bath, and Portland stones fresh from the quarry have been tested, but with- 

 out finding more than a trace of ready-formed sulphate, whereas scrapings taken 

 from the decayed portions of the stone of the New Palace at Westminster were 

 bitter to the taste, in consequence of the comparativel}- largo amount of sidphatc 

 of magnesia formed durhig a few years' exposure to the sulphurous gases occurriug 

 in a metropolitan atmosphere. Caen stone from several buildings and localities, 

 Portland stone, and even old faces of chalk clifi'in the neiglibourhood of Woolwich, 

 were in like manner found to contain appreciable quantities of the sulphate of 

 lime, having rmdoubtedlj^ a similar origin. A close examination into the circum- 

 stances attending the decay of stone at the Houses of Parliament invariably shows 

 an increased liability to corrosion under the projecting eaves and mouldings, and 

 at such sheltered parts of the stone surfaces as are usually covered with soot and 

 dust, and are in a position to retain for the longest period the moisture absorbed 

 during a season of rain. In many cases the disintegrated stone exhibits white 

 crystals of the sulphate of magnesia, which alternately dissolving and reciystal- 

 lizing in the pores of the stone, may be conceived to exert a disruptive action 

 sufficient to account for the scaling and fracture of the dolomite, which has been 

 so often observed. With the view of overcoming some of these difficulties, the 

 author submitted a plan to the lioyal Commissioners charged with inquiring into 

 the decay of stone at Westminster, in May 1861, which consisted in the applica- 

 tion to the cleaned surfaces of the stone of an aqueous solution of supei-phosphate 

 of lime — a salt remarkable for its action in hardening the surfaces of chalk, Caen 

 stone, or other calcareous building-stone to which it may be applied, either by 

 brushing or immersion, and which acts upon the carbonate of lime in the stone, 



