proceedings of the polytechnic association. 653 



Improved Baume Scale. 



This improved scale, as now made in this country, and used by the 

 dealers in coal oil and petroleum, consists of a hollow glass tube about one 

 foot long, closed at both ends, and so weighted as to sink vertically, when 

 set in oil, to a scale which has a range sufficient to include oils and the 

 lighter liquid products of crude petroleum. The zero or lowest point on 

 this scale corresponds with 1 on the ordinary hydrometer, marking the 

 specific gravity of water. From this point the counting is inverted — that 

 is, the lighter the liquid the higher the number, while on the common hydro- 

 meter the specific gravity of such liquid would be designated by a decimal 

 fraction. The comparative graduation on these scales will be understood 

 ■when it is stated that *I0 on the Baume corresponds with 700 on the com- 

 mon hydrometer, which marks the specific gravity of a liquid having 

 •l-lOths the weight of water. Below this scale is a mercurial thermometer, 

 having the zero point of its scale at the point where the mercury indicates 

 a temperature af G0° Fahrenheit — the standard of heat at which all mea- 

 surements of the density of liquids are made. From this point the scale 

 is graduated above and below, every unit corresponding with ten degrees 

 Fahrenheit. This scale denotes the number to be added to the hydrometer 

 measurement when it is made at a temperature below GO" degrees Fahren- 

 heit, or below the zero point of this attached scale, and the number to be 

 deducted when the measurement is made at a temperature higher than 60° 

 Fahrenheit. For example, if, in measuring an oil, the Baume scale stands 

 at 39 and its temperature is 30°, marked by 3, being 3 times 10 degrees 

 below the 60° Fahrenheit, this number, 3, is added to 39, and the oil is said 

 to be measured by 42 at the standard temperature; if, on the other hand, 

 this oil should be measured by 45 while the temperature is at 90° Fahren- 

 heit, 3 must be deducted for the excess of temperature — thus we have 42 

 as its measurement at 60° Fahrenheit. The mo^t correct method is to place 

 in water at 60° a glass tube, open at the top, containing the oil to be 

 tested — the Baumd number measuring this will need no correction for tem- 

 perature — yet the immense trade iu petroleum requires the use of the 

 improved scale described. 



A Gun Test. 



M. Decker thinks it possible to determine whether a gun has been fired, 

 and very nearly the number of times, by examining the chemical changes 

 produced by the combustion of the gunpowder, which leaves, both on the 

 interior and exterior of the gun, a blackish blue deposit. The rust of a 

 gun that has been used is different from one that has never been fired. 



A New Planet. 

 A new planet was discovered on the 2d of February last by N. Poyson, 

 Director of the Observatory at Madras. It is the 80th of .the series, and 

 has received the name of Sappho. 



The Production of Sulphur. 



M. P. Bianchi gives, in the Moniteur ScieMifique, some interesting statis- 

 tics in relation to the production of sulphur in Italy. The annual yield is 



