248 ANNUAL OF SCIENTIFIC DISCO VEEY. 



mmations gave for a burner of peat gas a light equivalent to 23 J candles; 

 and the same burner with coal gas, 6-^ candles. The illuminating power of 

 the pure oil from peat, the illuminating material par excellence, has been found 

 at equal pressures 705, the intensity for coal gas being 100 : an'd with equal 

 volumes their numbers are as 756 : 100. Silliman's Journal. 



ARTIFICIAL GTJTTA-PERCHA AND INDIA-RUBBER. 



The following communication was read before the British Association by 

 M. Claussen : 



" In the course of my travels as botanist in South America, I had occasion 

 to examine the different trees which produce- the India-rubber, and of which 

 the Hancornia speciosa is one. It grows on the high plateaux of South 

 America, between the tenth and twentieth degrees of latitude south, at a 

 height from three to five thousand feet above the level of the sea. It is of 

 the family of the Sapotacese, the. same to which belongs the tree which pro- 

 duces gutta-percha. It bears a fruit, in form not unlike a bergamot pear, and ' 

 full of a milky juice, which is liquid India-rubber. To be eatable this fruit 

 must be kept two or three weeks after being gathered, in which time all the 

 India-rubber disappears or is converted into sugar, and is then in taste one 

 of the most delicious fruits known, and regarded by the Brazilians (who caE 

 it Mangava) as superior to all other fruits of their country. The change of 

 India-rubber into sugar led me to suppose that gutta-percha, India-rubber, 

 and similar compounds, contained starch. I have, therefore, tried to mix it 

 with resinous or oily substances, in combination with tannin, and have suc- 

 ceeded in making compounds which can be mixed in ah 1 proportions with 

 gutta-percha or India-rubber -without altering their characters. By the fore- 

 going ic will be understood that a great number of compounds of the gutta 

 peroha and India-rubber class may be formed by mixing starch, gluten, or 

 flour with tannin and resinous or oily substances. By mixing some of these 

 compounds with gutta-percha or India-rubber, I can so increase its hardness 

 that it will be like horn, and may be used as shields to protect the soldiers 

 from the effects of the Minis balls, and I have also no doubt that some of 

 these compounds, in combination with iron, may be useful in floating batteries 

 and many other purposes, such as the covering the electric telegraph wires, 

 imitation of wood, ship-building, etc." 



IMPROVEMENTS IN THE SIZING OF PAPER. 



The following is a description of a new process for sizing paper, invented 

 by Dr. J. Macadam, of Glasgow. The plan is more particularly applicable in 

 the manufacture of such kinds and qualities of paper as arc partially or en- 

 tirely "resin sized" and machine made, and ii r.-i;-ists in the partial or total 

 substitution of aqueous solutions of single sulphates, or of other binary com- 

 pounds, for the double sulphate of potash and alumina, known by the name 

 of alum, usually employed according to the present system of manufacture. 

 The acid best suited for this purpose is sulphuric acid, and is employed in 



