GUNPOWDER 767 



tice. In France, whore a heavy tax is laid on sporting powders, this difference of 

 composition prevents the cheap blasting powder from being used in fowling-pieces. 



MODES OF ESTIMATING THE PROJECTILE FoECE OF GUNPOWDER. 



The usual mode of determining the propulsive force of powder is by ascertaining 

 the distance to which it can throw a ball of known weight. The instrument used 

 in this country for this purpose consists of an 8-inch mortar charged with 2 ounces of 

 powder, the balls being in each case of the same size and weight. The French use 

 for the purpose an iron mortar, elevated at an angle of 45. The mortar is 7'5 inches 

 in diameter. The ball is of bronze, and is only 0'067 inch smaller than the bore 

 of the gun ; the windage is, consequently, very small. The charge of powder being 

 3-2 ounces, and the weight of the ball 65 Ibs., the latter should be thrown not less 

 than 437*5 yards. 



The force of powder may also be estimated by means of an instrument, called a 

 pendulum -gun. It consists of a gun-barrel hung at the lower end of a pendulum, so 

 arranged that the amount of angular deviation caused by the recoil may be measured ; 

 the balls may also be fired into a cup suspended to a similiar pendulum. The data ob- 

 tained serve to enable the rapidity of motion of the ball, at the moment of discharge, 

 to be calculated by means of formula contrived for the purpose. 



ON THE ANALYSIS OF GUNPOWDER. 



Several methods have been given by various chemists for the analysis of gun- 

 powder : the following, on the whole, appears the most effective : The percentage of 

 water is, in the first place, to be determined by drying in vacuo over sulphuric acid, 

 until no more diminution of weight occurs. The dried powder, or a fresh quantity, 

 is then to be washed on a filter with boiling water, until nothing more is dissolved out. 

 The residue is to be dried below 212 and weighed ; the loss is the nitre. If pre- 

 ferred, the solution of the nitre may bo evaporated to dryness, and the residue 

 weighed. The mixture of charcoal and sulphur is then to be digested in a stoppered 

 flask, with bisulphide of carbon ; this will dissolve out the sulphur, and leave the 

 charcoal. The loss of weight of the dry mixture of sulphur and charcoal will enable 

 the percentages of sulphur and charcoal to be calculated. If it be desired to know 

 the quality of the charcoal, a combustion of it may be made with a mixture of chro- 

 mate of lead and bichromate of potash. Ordinary charcoal contains from 69 to 74 of 

 carbon, 3'9 to 5'5 hydrogen, 0*5 to 3'0 per cent, ashes. It has been attempted to dis- 

 solve out the sulphur with sulphite of soda, or caustic potash ; but these methods in- 

 volve several sources of error. 



Good gunpowder should not lose more than 1 per cent, of moisture on drying. It 

 should not leave alkaline globules, when exploded on a clean metallic plate. The 

 specific gravity of a good powder should not be less than 1'755 ; it is sometimes as 

 high as 1'840. The denser the powder the better it endures transportation. As the 

 density cannot be taken in water, owing to the solubility of the nitre, turpentine or 

 benzole must be substituted, a correction being made for the difference in density of 

 the fluid medium. 



Horsley's and Erhardfs Gunpowder. In the ' Chemical News,' August 16, 1862, we 

 find a short paper ' On an Explosive Compound,' by John Horsley, F.C.S. ' If nine 

 parts of well-dried and finely-powdered chlorate of potash be mixed with three parts 

 of fine powdered galls, a highly explosive compound is formed, which needs no granu- 

 lation. As it will not admit of trituration in a mortar, the mixture should be made 

 on paper by means of a bone spatula, or by passing it through a fine brass sieve. The 

 strength of common gunpowder may be increased by working up with the powdered 

 meal about 12 per cent, of powdered galls, and regranulating it. I have been ac- 

 quainted with this for several years, but never published it before.' 



Dr. Erhardt has yet more recently patented a, powder, the peculiarity of which is 

 that the ingredients are kept apart until they are required for use. This appears to 

 be in one packet (chlorate of potash), and in the other, tannin. These are mixed 

 together in certain proportions, and diluted with powdered anthracite, according to 

 the purpose for which it may be required. As a blasting powder in quarries, Dr. 

 Erhardt's powder is said to possess extraordinary power. 



Schultze's Whits Gunpowder is a tri-nitro-cellulose, prepared from sawdust by the 

 following process. The sawdust is first boiled for three or four hours with a weak 

 solution of soda, and then boiled a second time with a fresh lot of the same solution. 

 It is then washed in running water, afterwards steamed for fifteen minutes, and then 

 again washed in running -water for twenty-four hours. It is now bleached with 

 chlorine or chloride of lime, boiled in water, once more washed in a stream, and then 



