Progress of Invention. 77 



nary state being a combination of both. It bas been proved by- 

 recent researches that the oxygen in peroxide of barium is in the form 

 of ozone, and that in the peroxide of manganese in the form of 

 antozone. The consequences which follow from these discoveries 

 are of a most interesting description : since if the two kinds of 

 oxygen enter into combination, it is probable that the elements 

 with which they combine exist in two allotropic states ; and the 

 inference may indeed be extended indefinitely, so as to lead to a 

 belief that also all the elements, and perhaps all their compounds, 

 are capable of existing in two opposite allotropic states. The facts 

 which demonstrate that the oxygen elements in the peroxides of 

 barium and manganese are in very different states, are very remark- 

 able, and are such as admit of no doubt. Thus the oxygen in the 

 peroxide of barium has a less affinity for hydrogen than chlorine, 

 since, when it is acted on by the latter, hydrochloric acid will be 

 formed, oxygen being given off; while on the contrary, hydrochloric 

 acid is decomposed by peroxide of manganese, chlorine being 

 evolved. It is worthy of remark that the oxygen given off by the 

 peroxide of barium is in the form of ozone. Again, if peroxide of 

 barium is treated with hydrochloric acid, peroxide of hydrogen will 

 be formed ; but if peroxide of manganese is treated with the same 

 acid, ordinarily, water will be formed, and chlorine evolved. Sulpho- 

 vinic acid, if heated in presence of peroxide of barium, affords ether, 

 bicarburet of hydrogen, and sulphurous acid ; but if in presence of 

 peroxide of manganese, aldehyde. Peroxide of hydrogen may be 

 formed by means of either peroxide of barium or peroxide of manga- 

 nese ; but the two peroxides of hydrogen thus obtained are very 

 different, since each will be decomposed by the peroxide employed 

 in forming the other ; and, what is still more remarkable, they will 

 decompose each other. 



Miscellaneous. — Damping Apparatus for Copying. — In copying 

 letters, the most troublesome portion of the process consists in 

 damping the paper : this is greatly facilitated by means of a simple 

 apparatus recently invented in Germany. It consists of a hollow 

 perforated roller covered with linen, and rotating on a tube con- 

 nected with the handle, which serves as a reservoir for water. 

 When the roller is in use, the water flows from the handle into 

 the tube, thence into the perforated roller, and thus the linen is 

 kept wet while being rolled over the paper. When the instrument 

 is not required, it is left in such a position as causes the water to 



flow back into the handle. Purification of Water. — There is good 



reason to believe, from certain experiments recently made, that 

 any kind of water may be freed, not only from the impurities it 

 contains in suspension, but also those it holds in solution, and may 

 thus be made fit for drinking, by adding to it a very small amount 

 of a solution of permanganate of potash, and then filtering it 

 through a layer of magnetic oxide of iron and carbon, a few iuches 

 thick. The required mixture may be obtained by heating in a close 



vessel red oligist ore and a small quantity of sawdust. Petroleum 



as Fuel. — In the ordinary modes of using petroleum as fuel, there is 

 very frequently produced a very large quantity of black smoke, 



