BAIR.D &TATLOCK: (LONDON) LTD. 



5222 Jackson's Apparatus, for the Photometric Determination of Sulphates in Cement 



5223 Extra Tubes, marked to 240 millimetres, for above . . . . . . . . each 



5224 Extra Standard Candles, for above . . . . . . . . . . 



Extract from " Portland Cement : Its Composition, Testing, and Analysis," by RICHARD 

 K. MEADE. 



Jackson has devised a rapid photometric method for determining sulphuric acid, which is very convenient for 

 checking this constituent in a large number of samples. 



The apparatus used in this method is shown in figure. Above is a glass tube, closed at the bottom, and 

 graduated in millimetres depth. The brass holder for this tube is open at the bottom, so that the glass tube rests 

 on a narrow ring at this point. The candle below is so adjusted by means of a spring that the top edge is always 

 just three inches below the bottom of the glass tube. The English Standard Candle is preferred, but a common 

 candle of the same size may be used. This candle must always be properly trimmed, and the determination be 

 made rapidly so as not to heat the liquid to any extent. The most accurate work is obtained in the dark room, 

 and the candle should be so placed as not to be subjected to a draught of air. Care should be taken to keep 

 the bottom of the tube clean, both inside and out, so as not to cut out any of the light. 



To determine the sulphate in a cement, weigh out one gram, correct to centigrams, and rub up thoroughly 

 with a glass rod in a small porcelain dish or casserole, with two cubic centimetres of strong hydrochloric acid. 

 Add about ten cubic centimetres of water, and heat to boiling. Filter, and wash with a small amount of hot 

 water, into a 100 c.c. graduated Nessler jar, and fill with cold water nearly to the 100 c.c. mark. 



If necessary, suction may be employed in filtering, but usually a folded rib filter will do. Now add two 

 grams of solid barium chloride crystals, and make up to the 100 c.c. mark with cold distilled water. Pour 

 back and forth from the tube to a beaker until all of the barium chloride is dissolved. The solution is now ready 

 for examination. 



The candle is trimmed and lighted ; the solution is poured back and forth to get a thorough mixture of the 

 precipitate of barium sulphate ; and the glass tube is placed in position in the holder. The liquid containing the 

 precipitate is now poured into the graduated tube until the sight of the image of the flame of the candle is just 

 visible. Then pour in a few drops at a time until it just disappears from view. The height to which this solution 

 stands in the tube (reading the bottom of the meniscus) is then taken, and from this reading the percentage of 

 sulphates present in the cement may be read directly from the following Table : 



FOR THE DETERMINATION OF SULPHATE IN CEMENT. 



140 

 050 

 008 



5222 



5225 Candles, standard 



each, 8d. ; per Ib. 040: 



CROSS STREET HATTOX GARDEN, E-C- 



