T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . found sucrose in appreciable quantity. The analyses were made by Dr. B. G. Hartmann and Mr. John R. Eoff. WM. B. A ~ W O O D . STONEHENCE LABORATORIES, CHARLOTTESVILLE, V A . ,
July 15, 1910.
THE SCOTT OIL TESTER. Scott's oil tester is a flash point apparatus for oils, varnishes, ether, alcohol, gasoline, turpentine, etc. While it has just made its appearance on the open market it has been in constant use for several years in the laboratory of its designer, Mr. D. G. Scott, of Chicago. I t is electrically ignited and does away with the errors of personal equation, every determination being made under exactly the same conditions. One of the peculiar features of this apparatus lies in the electrodes which are so fashioned that when properly adjusted the spark travels backward and forward across a considerable portion of the surface of the oil so fast as to practically form a rjbbon of fire about a quarter of an inch wide. The combustion or flash chamber
is so arranged that determinations may be made in freezing mixtures or high flash point determinations may be made over a naked flame. The amount of sample needed is exceedingly small, precluding danger from fire and thus making it particularly desirable for use in paint, oil and varnish laboratories. The whole apparatus is self-contained, including batteries, etc., and occupies a space of only 8 by IO inches on the table and is about 16 inches high. I t s operation is very simple and its convenience apparent. I t is durable and easily cleaned and its compactness and stability of design are such that it is as easily placed on the table ready for use or removed to the wall case for storage as a bottle or jar of the same size. The first notice of this apparatus occurs in the new catalog of Messrs. E. H. Sargent & Co., of Chicago, who manufacture the instrument under the direction of Mr. Scott.
Nov., 191
CHROME PAINT ANALYSIS. The chrome yellow paints on the market very frequently contain a number of constituents other than lead chromate, and the lack of any definite procedure in ~ a l y t i c a works l dealing with paints has led to the following attempt to arrive a t a satisfactory scheme of analysis. A mixture containing the following ingredinets was made: BaSO,, SO,, PbCrO,, PbO, Fe,O,, ZnO, CaSO, and CaCO,. While it is not likely that all of these constituents would ever be present in a single paint, yet all of them have been found in chrome paints, and the following scheme of analysis can be applied to determine any or all of them. ( I ) The silica and barium sulphate are separated by dissolving I g. of the paint in conc. HC1 and evaporating to dryness twice with HC1. A few drops of HC1 are then added and about IOO cc. hot water and the solution brought to a b&l, allowed to settle, decanted through a filter and the process repeated. The insol. residue, which should then be white (if not a few drops of HC1 are added and the process repeated until it is), is filtered off, washed with hot water several times and ignited in the blast in a platinum crucible and weighed. This gives BaSO, and SO,. A few drops of H,SO, and some hydrofluoric acid are added and the SiO, volatilized, and the BaSO, weighed. The SiO, is estimated by the loss in weight. (2) The calcium present as sulphate is obtained from the filtrate from the BaSO, and SiO,. This is brought to a boil and the sulphate precipitated with BaCl, in the usual manner. After settling, the BaSO, is filtered off and washed thoroughly with very hot water (care must be exercised to wash out all Lhe PbCl,), ignited and weighed. The BaSO, is calculated to CaSO,. (3) The zinc oxide and calcium carbonate are obtained by treating I gram of sample with strong acetic acid, boiling, then diluting and filtering. The zinc oxide, all calcium salts and most of lead present as oxide pass into solution. The zinc and lead are precipitated with H,S and filtered off, redissolved in hot dilute HC1 and several grams of sodium acetate added; the lead is then precipitated as chromate by adding small excess of K,CrO,. This is filtered off and the zinc precipitated in the filtrate as carbonate by adding a n excess of Na.&O, and digesting. The precipitate is filtered off, ignited and weighed as ZnO. The Ca which is in the filtrate from the Zn and Pb is precipitated as oxalate after making alkaline with ",OH, filtered, ignited and weighed as oxide. From total CaO is subtracted CaO present as CaSO,, and the remainder calculated to CaCO,. (4) The ferric oxide is obtained by treating I g. of the paint with about IO g. NaOH and IOO cc. water, heating to the boiling point, filtering and washing with hot water. The filter paper containing Fe,O,, BaSO,, SiO, and PbO is then ignited slowly in a porcelain crucible (to prevent its sticking to sides of crucible) and the residue digested with 5 cc. hot conc. HCl and transferred to a beaker with 50 cc. of water. The BaSO, and SiO, are filtered off and the filtrate almost neutralized with ",OH and the lead precipitated as sulphide and filtered off. The H,S is boiled from the filtrate, the iron oxidized to ferric condition with a little HNO,, precipitated with ammonia and weighed as Fe,O,. The filtrate from FezO3, BaSO,, etc., is used for the estimation of lead chromate. It is acidulated with acetic acid, when the insol. PbCrO, is precipitated, filtered through Gooch crucible, dried on,hot asbestos plate and weighed a s PbCrO,. ( 5 ) To obtain PbO, I gram of paint is treated as for BaSO, and SiO,, the filtrate evaporated to dryness, taken up with a few drops of HC1, about IOO cc. hot water added and the solution boiled until clear green, adding more HC1 if necessary. About 5-10 grams sodium acetate are then added to remove free hydrochloric acid. A t this point the color of the solution
