254 



SCIENCE 



N. S. Vol. XXX. No. 764 



three 100 c.c. portions of ether. The unwashed 

 ei/her extract is distilled rapidly over steam or by 

 electric stove to the volume of about 5 c.c. and 

 the residue exhausted by a current of air. This 

 extract is dissolved in a little alkaline water and, 

 after transferring to a Squibb separator, and 

 acidifying with hydrochloric acid, is shaken out 

 with 40, 30, 20 and 10 c.c. successive portions of 

 chloroform. The chloroform extract is washed 

 with 30 c.c. water and transferred to a suitable 

 container to which is added 100 c.c. recently boiled 

 water and a few drops of phenol-phthalein. 



The mixture is then titrated with N/20 NaOH, 

 shaking well after each addition of alkali. Each 

 cubic centimeter of N/20 used has a benzoic acid 

 value of .0061. A correction is made for blank 

 chloroform water mixture. The necessity for 

 using ether will not arise when chloroform will 

 readily make the extraction. 



The advantages of the method are as follows: 

 First, economy in time and in recovery of sol- 

 vents; second, avoidance of tenacious chloroform 

 emulsions; third, interfering organic acids elim- 

 inated; fourth, loss of benzoic acid reduced to a 

 minimum. 

 The Determination of Sucrose and Lactose in 



Sweetened Chocolate: W. D. Bigelow and M. 



C. Albeech. 



The method is proposed to obviate the diffieul- 

 tiea ordinarily experienced in the extraction of 

 fat preliminary to the determination of sugar and 

 in the volume of the lead precipitate. A normal 

 weight of the sample (26 grams per Ventske in- 

 strument) is placed in a 100 c.c. sugar flask, 

 90 c.c. of water added and the flask heated with 

 occasional shaking in a water-bath. After the air 

 in the flask is heated a stopper is inserted. When 

 the temperature has reached 70 or 80°, 10 c.c. of 

 basic lead acetate is added and the flask thor- 

 oughly shaken and allowed to cool. The mixture 

 is then filtered and the clear liquid polarized and 

 its specific gravity taken. From a table the 

 amount of sucrose is read off from the polariza- 

 tion alone. In the presence of lactose the solu- 

 tion is inverted and again polarized, this time at 

 86°. 

 Composition ami Treatment of Lake Michigan 



Water: Edward Babtow and Lewis I. Bibd- 



SAIi. 



A zone of pollution has been found to extend 

 into Lake Michigan along the shore of Indiana 

 and Illinois. All communities are not able to 

 extend their water intakes beyond this zone of 

 pollution or to divert their sewage as Chicago 



does. Filtration must be used to get a pure 

 water. The average composition of the water was 

 determined and experiments made to learn the 

 action of various eoagulents that may be used in 

 connection with mechanical filtration. 



Lime, sulphate of aluminum, sulphate of iron 

 and sodium carbonate were used either alone or 

 in combination. 



The results showed the best results with sul- 

 phate of aluminum were obtained when 2* grains 

 per gallon were used. Two grains of lime could 

 be substituted for one grain of sulphate of alu- 

 minum at a saving of $1.34 per million gallons. 

 Sulphate of iron could replace the sulphate of 

 aluminum at a further saving of $1.08 per mil- 

 lion gallons. Special care must be taken, how- 

 ever, when lime or sulphate of iron is used. 



The Examination of Dried Fish: B. H. Smith. 



Cusk and haddock are often substituted for 

 cod in boneless and shredded so-called " codfish " 

 because of their low price and because the prepa- 

 rations made from these fish resemble those of 

 cod, making the detection of the substitution a 

 matter of some difficulty. Hake and pollock are 

 less frequently used, primarily because the red- 

 dish color of the former and the brownish color 

 of the latter indicate the presence of these fish. 



In an attempt to differentiate chemically the 

 several varieties of closely allied salted fish the 

 body oils were extracted by means of carbon- 

 tetrachloride from desiccated ground samples, rep- 

 resenting, in the case of cod, variations of geo- 

 graphical origin and methods of curing, and the 

 iodin number, the refractive index, and, in some 

 instances, other determinations, were made. The 

 iodin numbers in all eases were lower than those 

 of the liver oils of the same variety of fish and 

 even greater variability was evidenced. The re- 

 suits obtained by the Hanus method on the cod 

 samples varied from 85 to 137, which wide range 

 is believed to be due in part to the complex com- 

 position of the natural oil and in part to the 

 oxidizing infiuenoe of the salting and drying 

 process; the cod substitutes gave iodin numbers 

 of from 112 to 120. 



The refractive indices of the oils from the cod 

 samples varied from 1.5020 to 1.5043 at 25°, and 

 those of the other varieties of fish from 1.4890 

 to 1.5000 at the same temperature. The " re- 

 ducing substances " of the fish, which were de- 

 termined by the method of Williams, Journal of 

 Chemical Society, LXXI., 649, who reported con- 

 siderable variation in different varieties, were 

 found in but small amounts and are apparently 



