472 Progress of Invention. 



admits no longer of doubt. They had the same origin as the bog 

 ores which are still being formed in the Swedish lakes : and 

 which consist of carbonate of the protoxide, formed from hydrated 

 peroxide by the organic matters with which these lakes abound. 

 This important fact has been established, by a fossil belonging to 

 the genus TJnio having been found among these ores, and exhibiting 

 the same constituent as they, and also the important peculiarity of 

 belonging to a genus of mollusca, all the species of which are found 

 exclusively in fresh water. "We may infer, therefore, without hesi* 

 tation, that these ores are a fresh- water formation, due to causes 

 which, to a limited extent, are still in operation. 



Miscellaneous. — Applicability of the Electric Light to Light- 

 houses. — The superiority of the electric light for the purpose of 

 lighthouses has, for a considerable period, admitted of but little 

 doubt ; but the French Government seem to consider the question 

 regarding it as now set at rest. For some time past, magneto- 

 electric machines, with four discs, have been in iise at the lighthouse 

 of Cape de la Heve : producing a light in every way greatly 

 superior to that obtained by the old method, and visible at the 

 distance of twenty miles. They have now been replaced by others, 

 having six discs; capable, when required, of giving a light equivalent 

 to 10,000 cancel burners, or 100,000 candles, and visible at the 

 distance of twenty-seven miles. Ozone. Some important in- 

 formation regarding ozone has recently been obtained. ' The 

 researches of M. Fremy have led to the conclusion that our methods 

 of detecting it in the atmosphere are not to be relied on. It is 

 ■ certain that the tests for ozone are similarly affected by a variety 

 of substances, such as the oxygen compounds of azote, ammonia, 

 formic acid, the products of combustion, and other bodies, many of 

 which, including dust, are present in the atmosphere. He advo- 

 cates the employment of silver as the reliable test ; its surface being 

 oxidized if moisture containing ozone is passed over it. Others 

 also, and among them M. Berigny, have investigated this important 

 subject. The researches of M. Soret have rendered it extremely 

 probable that ozone is oxygen is an allotropic state, and having a 

 density one and a half times that of normal oxygen. He found that 

 when oxygen is ozonized, its volume is diminished ; that when 

 ozonized atmospheric air is acted on by iodide of potassium or other 

 oxidizable bodies, the ozone is absorbed, but the volume is not 

 changed ; that, under the influence of heat, ozonized air so expands 

 that the increase of volume just equals the amount of oxygen 

 capable of uniting with iodide of potassium ; and that either oil of 

 turpentine or oil of cinnamon absorbs ozone without decomposing 

 any of it — which is not the case with the other bodies that absorb 

 it. He found that when ozonized oxygen is treated with oil of 

 turpentine, the volume is diminished to an amount very nearly 

 equal to twice that occupied by the gas absorbed by the iodide of 

 potassium, and also to twice the increase of volume produced when, 

 the ozone is decomposed by heat. 



