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New green pigment
The Strength of Cast Iron Water Pipes.
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side the furnace, which prevented the "tears" from dropping, and caused them to run down the sides of the furnace inste'~d. The use " of a current of air for separating fine substances, to which reference had been made, was also adopted in the process of grinding sulphur for vulcanizing purposes. Mr. P. Rigby remarked, that the smoothing machine used at Messrs. Chance's works had been adopted for giving the smoothness of polished plate glass to sheet glass, as that was now required for many purposes, and particularly by photographers ; but hand smoothing never made the surface quite so smooth and uniform as was done by the machine. Pro. Mech. Eng. So¢.
New Green -Pigment. From the London Chemical News, No. 281.
Under the name o f " Green Cinnabar," Vogel describes a new color which is prepared in the following way : Prussian blue is dissolved in oxalic acid ; chromate of potash is added to this solution, which is then precipitated with acetate of lead. The precipitate, well washed, dried, and levigated gives a beautiful green powder. :By varying the proportions of the three solutions, various shades of green may be procured. Chloride of barium or nitrate of bismuth may be used in place of sugar of lead.--Chem. CYentral.Blatt. [Another mode of preparing ~his color will be found at page 182, vol. ix, C/~em. News.]
The Strength of Gust Iron Water _Pipes. From the London Mechanics' Magazine, November, 1864.
Before the introduction of cast iron, water pipes were made in England of fig tree woodi and straight pipes, from twelve to twenty feet in length, were bored out of this material. Such pipes are now very scarce here, but we have seen many in use for even rather large mining pumps in eastern Europe. Wooden pipes can be made from one and a half to eight inches in the bore, which is generMly one-third of the diameter of the pipe. The joints are, of course, upon the spigot and socket plan. Cast iron has now superseded wood for this purpose almost everywhere, although the introduction of such a strange material as tarred pasteboard is now being attempted for water pipes. The insides of cast iron pipes are generally varnished, or are sometimes covered with hydraulic cement in order to protect them from oxidation. It will be seen that the strength of the metal depends upon the pressure of the water and the diameter o~ the pipe. The thickness of a cast iron water pipe is never so great as to bring into play those peculiar conditions of tensions which exist, for instance, in the cylinders of hydraulic presses or of ordnance. A water pipe is simply strained like the comparatively thin cylindrical shell of a boiler, or of a steam pipe. A cylinder undergoing an interior pressure, which tends to either increase its diameter or to burst it, while the section of the metal is of equal thickness throughout, is a sufficiently simple
135
side the furnace, which prevented the "tears" from dropping, and caused them to run down the sides of the furnace inste'~d. The use " of a current of air for separating fine substances, to which reference had been made, was also adopted in the process of grinding sulphur for vulcanizing purposes. Mr. P. Rigby remarked, that the smoothing machine used at Messrs. Chance's works had been adopted for giving the smoothness of polished plate glass to sheet glass, as that was now required for many purposes, and particularly by photographers ; but hand smoothing never made the surface quite so smooth and uniform as was done by the machine. Pro. Mech. Eng. So¢.
New Green -Pigment. From the London Chemical News, No. 281.
Under the name o f " Green Cinnabar," Vogel describes a new color which is prepared in the following way : Prussian blue is dissolved in oxalic acid ; chromate of potash is added to this solution, which is then precipitated with acetate of lead. The precipitate, well washed, dried, and levigated gives a beautiful green powder. :By varying the proportions of the three solutions, various shades of green may be procured. Chloride of barium or nitrate of bismuth may be used in place of sugar of lead.--Chem. CYentral.Blatt. [Another mode of preparing ~his color will be found at page 182, vol. ix, C/~em. News.]
The Strength of Gust Iron Water _Pipes. From the London Mechanics' Magazine, November, 1864.
Before the introduction of cast iron, water pipes were made in England of fig tree woodi and straight pipes, from twelve to twenty feet in length, were bored out of this material. Such pipes are now very scarce here, but we have seen many in use for even rather large mining pumps in eastern Europe. Wooden pipes can be made from one and a half to eight inches in the bore, which is generMly one-third of the diameter of the pipe. The joints are, of course, upon the spigot and socket plan. Cast iron has now superseded wood for this purpose almost everywhere, although the introduction of such a strange material as tarred pasteboard is now being attempted for water pipes. The insides of cast iron pipes are generally varnished, or are sometimes covered with hydraulic cement in order to protect them from oxidation. It will be seen that the strength of the metal depends upon the pressure of the water and the diameter o~ the pipe. The thickness of a cast iron water pipe is never so great as to bring into play those peculiar conditions of tensions which exist, for instance, in the cylinders of hydraulic presses or of ordnance. A water pipe is simply strained like the comparatively thin cylindrical shell of a boiler, or of a steam pipe. A cylinder undergoing an interior pressure, which tends to either increase its diameter or to burst it, while the section of the metal is of equal thickness throughout, is a sufficiently simple