Salt hopper

The crystals of rock-salt are nearly always cubes or small octahedrons. When the crystals form on the surface of evaporating brine, distinctive hopper-shaped crystals resembling hollow quadrilateral pyramids are developed the inner surface appears to be arranged in a series of steps. D. I. Mendeleeff1 explains the formation of hopper salt crystals as follows ... 

Alberger chlorure de sodium common salt hopper salt natural halite rock salt saline salt sea salt table salt. 

Ref 2). This was followed by Will in 1906 (Ref 3), Silberrad and Phillips in 1908 (Ref 4), and Kast in 1911 (Ref 5). More recently (1938), Hopper of PicArsn (Ref 6) detd and described the expl properties of the following metallic picrates Ai, Cd, Cr, Cu, Fe+3, Fe+2, Na, Ni and Zn. In general,he prepd the salts as cryst hydrates from aq solns by methods outlined by Silberrad Phillips, and Kast. These were then dehydrated by heating at temps of 80 to 150°, depending on the ease with which the w of crystn could be driven off, to obtain the desired degree of hydration... 

According to Hopper, the relative sensitivity of metallic picrates depends largely upon the amts of w of crystn present. The highly hydrated forms are wry insensitive, the lower hydrates are in general more sensitive, and the anhydr forms most sensitive. The anhydr salts, with the exception of Na, Amm, Al and Fe+2, are more sensitive to impact than PA. Anhydr Cu, Zn and Cd picrates are only slightly more sensitiw, while anhydr Ni picrate is especially sensitive, lying in the sensitivity range between MF and Tetryl... 

Cadmium Picrate. [C6H2(N02)30] 2Cd, mw 569.70, N 14.76%, yel powd which explds violently at 336—41°. Was obtained by heating one of its hydrates at 80—150°. Silberrad and Phillips (Ref 2) reported on the hepta- and pentahydrates, while Hopper (Ref 3) reported on the octahydrate. Sensitivity of the anhydr salt is 12" vs 14" for TNT, as detd with the PicArsn app using a 2kg wt. The value for the octahydrate is 35", making it less sensitive than BlkPdr dust... 

In the production of formic acid, a slimy of calcium formate in 50% aqueous formic acid containing urea is acidified with strong nitric acid to convert the calcium salt to free acid, and interaction of formic acid (reducant) with nitric acid (oxidant) is inhibited by the urea. When only 10% of the required amount of urea had been added (unwittingly, because of a blocked hopper), addition of the nitric acid caused a thermal runaway (redox) reaction to occur which burst the (vented) vessel. A small-scale repeat indicated that a pressure of 150-200 bar may have been attained. A mathematical model was developed which closely matched experimental data. 

Recrystallizer A process for reciystallizing sodium chloride from brine. Rock salt is dissolved in brine heated with direct steam. The solution is then partially evaporated under reduced pressure. Invented in 1945 by C. M. Hopper and R. B. Richards at the International Salt Company, Scranton, PA. See also Alberger. 

Lead Salts of Nitrocompounds. Hopper (Ref), at PicArsn, prepd and characterized Pb dinitro-resorcinate, Pb dinitrophenolate, and Pb di-nitrophthalate as possible substitutes for MF in priming compns. Only the dinitroresorcinate... 

Combstn of compressed MF in vacuo) J) Pepin Lehalleur(1935), p 141 (Structural formulas proposed for MF) 141-42(Reactions of formation MF from Hg, nitric acid alcohol 143-44(Liebig s method of manuf MF) 144—45 (Chandelon method of manuf MF) 148—49(Driers for MF) K) J.D. Hopper, PATR 480(1934)(Study of Pb salts of nitrocompds as substitutes for MF) L) J. D. Hopper, PATR 624(1935) (Development of detonating compds to replace MF) M) L. Majrich, SS 31, 147—48 (1936)(MF can be obtd in 99.6% purity by dissolving crude product in a mist of equal vols of monoethanolamine and ammonia and ppm with dil AcOH) N) Sancho (1941),... 

From these troughs the partly-drained salt is conveyed to the hoppers of a number of adjacent millstones, where it is abraded and given out from the sluice in a pasty state these sluices deliver it into the boxes of other heavier millB placed below the former in a second tier. Finally, the white lead, thus reduced, passes through a third mill, and thence into a deep tub or vat which also receives a stream of water from tho pump and by means of a rotatiag agitator tho load is so mixed with the water, that it is carried off in tho sluice which... 

Grainer salt is made by surface evaporation of brine in flat pans open to the atmosphere. Heat usually is furnished by steam pipes located a few inches below tlie tank bottom. Crystals form at the surface of the brine and are held tliere temporarily by surface tension. Thus, they grow laterally for awhile and form thin flakes. But, as they grow, they tend to sink and this process imparts a peculiar, hollow pyramid-like structure to them. Such crystals are called hopper crystals. Ultimately, the crystals sink to the bottom where they are scraped to one end of the pan. The crystals are fragile and during handling they break up, finally assuming a flake-like shape. Thus, tlie term flake salt. 

---