128 REPORT 1861. 



fecting-powder, in which the properties of carbolic and sulphurous acid are 

 taken advantage of. This powder is used to prevent decomposition in 

 stables, cowhouses, and among accumulations of putrescible matter, and 

 generally for the prevention of decomposition in manures. A liquid is also 

 prepared with carbolic acid and lime-M'ater, which is applied for the purpose 

 of preventing decomposition in sewers, thus carrying out the idea first started 

 by one of us, of purifying whole cities by preventing the generation of gases 

 in sewer water, or among accumulations of refuse. This liquid is also used 

 to prevent the decomposition of animal matter when it cannot at once be 

 made use of, especially in the case of meat brought to market, or animals 

 that have died in the fields. The powder, which is called " M'Dougall's 

 disinfecting-powder," is simply a mixture of the sulphites of lime and mag- 

 nesia with the carbolates of the same beises. The carbolates of lime and 

 magnesia are formed by simply boiling carbolic acid for a long time with the 

 bases in a caustic state. The solution consists of carbolic acid dissoU'ed in 

 lime-water. It is extremely bulky ; still xvVo*-'^ ^o TrrVrrt'^ P^""* of t'^e bulk of 

 the sewer water is sufficient to disinfect the latter. The solution of the powder 

 has also been used to some extent in dissecting-rooms, where it immediately 

 destroys any noxious smell, and at once liberates the fingers of the operator 

 from the peculiarly nauseous odour which so often attaches to them. It has 

 also been found useful in the treatment of sores, as well as of dysentery. 

 M. Leraaire has lately read papers on tar oil and phenic acid ; but Man- 

 chester claims priority in the application and explanation of these prepa- 

 rations. 



Mr. M'Dougall has also applied carbolic acid to the destruction of para- 

 sitic insects on sheep, and has in many districts entirely driven out the 

 arsenical preparations by the use of this acid united with fatty substances. 

 Sheep dipped in it are not liable to be attacked by tick, even when left for 

 some months among other sheep infested with it. Foot-rot and other diseases 

 of sheep are also said to be prevented and cured by its use. 



Mr. Pochin has introduced lately a very extensive manufacture which has 

 greatly affected the mode of using alumina, and also the manufacture of 

 alum. The substance is called alum-cake. It is sulphate of alumina with 

 about 16 equivalents of water and silica. Very fine white clay is stirred 

 round with sulphuric acid of about 140*0 sp. gravity, then warmed to about 

 100° F., and poured into a square trough with moveable sides. In a few 

 minutes the action of the acid on the clay becomes very violent, and a 

 sulphate of alumina is formed with the silica of the clay intimately mixed. 

 If very strong sulphuric acid is used, the action becomes so violent that the 

 whole mass is thrown out of the trough. The whole hardens into a compact 

 mass difficult to break. To facilitate the fracture, wedges of iron were 

 pressed into the mass when soft, the sides of the trough were taken down, 

 and by striking the wedges the whole was broken into pieces. Now, how- 

 ever, a more elaborate machine is used to break it up into small portions. 



In this manufactured article there is a large quantity of alumina, viz. 12"8 

 per cent, in a soluble form ; the trouble of crystallizing is avoided, and the 

 silica is in no way injurious in most cases. In some cases, where alum is 

 used with resin for paper size, the addition of the silica is indeed consi- 

 dered an advantage. At any rate, the manufacture is constantly increasing ; 

 if silica be objected to, it is allowed to fall down, and a clear solution of 

 sulphate of alumina remains. 



