wns as follows : 1 ml. sniounta of the phosphnte standnrds were run into 13 mm. tubes, held firmly in n rnck on the reciprocating slinker ; 1 ml. of the molybdntc rengent, diluted to 5 ml. with wnter, \vns run into each tube nnd mixed by slinking for 15 sccs. 0.1 or 0.2 ml. stonnous oxnlnte wns then rmi in nnd mixed immediately by slinking by hnnd. Readings were made nt times of 1, 2, 5, 10 nnd 30 min. from shaking. With 0.1 nil. stnnnous osnlnte, maximum colour development wns renchcd in I minute, the blnnk developed appreciable colour, and there wns little difference betnecn the rendings for 7,s nnd 9 p.p.in. of pliospliorus. Grndunl fnding begnn a t 2 mins.
With 0-2 in]. stnnnous oxalnte, the higher standnrds date rengent made up with different strengtlis of ncetic ncid or liydrochloric acid. SLaiiilous chhiflc sohtion-O.1 g. pure tin dissolved in 2 ml. concentrntcd l~ydrochloric acid ns described by Holmnn nnd PollardP The soliition was prepnred fresh drdy nnd diluted ns required for use to 400 ml. to give 0.025% stannous.
Sodium siolybdale ~eagcnt-O.5% and 1.0% dissolved in (a) 0.35 nnd 1.75 N ncctic ncid, and (a) 1-25, 1.75, 2.0 and 2.5 N hydrochloric ncid. Nixing nnd ~nens~ircmeiits were made in glass tubes ns ilescribed previously, using 1 nil. phosplinte stnndnrd, 1 ml. molybdntc rengent The rengents were ns follows :- . from mixing.
TABLE I
Co~ripciri~nir of
S~rcEkcr drwn rcnciirigffnr .doachrch itr U.K.S., C c c U.K.S. ( r i d U.E.S. + CciCI, S a Stunnons Sodium Norninlity Clrlorido Molybdntu HCI 01 m 0.1 1 .0 0 . 1 1 -5 0 . I . > . 0 0.1 0.5 0-05 1.0 * Dickman and Brav. Ind. Enn. Chum. (Anal.). IMO, la. UIj.5.