An infinite number of questions in pure science remain to be decided by means of research. Is Electricity decomposible like radiant heat or light? {24} Are the "elementary substances" really compound bodies? Are they all compounds of Hydrogen? Are they all decomposed by very high temperatures, as compound substances are "disassociated" by less elevated temperatures? Under what conditions is Fluorine isolated? Do gases transmit heat by conduction? Under what circumstances is Light converted into Electricity? and into Magnetism? What is the actual size of an atom of Hydrogen? Does Light (without heat) expand bodies? What is the actual molecular arrangement of the atoms of Hydrogen at 60 Fahrenheit? What is the cause of the absence of metalloids in the Sun? What are the properties of Fluorine? What is the vapour density of Cæsium? Under what circumstances is heat wholly converted into mechanical power? &c., &c. All these discoveries when made, will probably, sooner or later, be productive of practical benefits to mankind. Nearly every manufacturer in this country is deriving, from scientific discoveries, advantages for which there has been little or no payment made to the discoverers. The makers of coal-tar-dyes, and dyers of wool and silk, are using Mitscherlich's discovery of nitro-benzine. Manufacturers of picric acid and "French purple" have enjoyed the fruits of the labours of Dr. Stenhouse. Makers of chlorate of potash and cyanide of potassium are profiting largely by the discoveries of Scheele, Gay-Lussac, and others. All the percussion cap makers {25} are indebted to Howard and Brugnatelli for fulminating silver. Railway-contractors, quarry-proprietors, and others, use nitro-glycerine discovered by Sobrero. Iron smelters are benefiting by the discovery of Bunsen, that 42 per cent. of the heat of the fuel was lost as combustible gases--these gases are now utilized. Telegraphists and electro-platers are also indebted to him for his voltaic battery. The producers of metallic magnesium owe the origin of their process to him as being the first to convert it into wire and make known its great light giving power. Multitudes of persons now use his well-known "Bunsen's burner" for heating, cooking, and other operations. The various telegraph companies, copper smelters, and makers of copper telegraph wire, are using Dr. Matthiessen's discovery of the influence of impurities on the electric conducting power of copper. Phosphorus-makers are reaping the reward of the labours of Gahn and Scheele. The makers of electro-plate and German silver are deriving profits from the labours of Faraday, who investigated electrolysis; of Gay Lussac, who discovered cyanogen; and of Cronstedt, who discovered nickel. Makers of Bessemer steel enjoy advantages derived from the spectrum discoveries of Kirchoff. Iron and copper smelters, metallurgists in general, dyers, calico printers, bleachers, brewers, makers of vinegar, red lead, varnishes, colours, soaps, green