214 



SCIENCE 



[N. S. Vol. LI. No. 1313 



the larger and most important part of the 

 United States, that is, between latitudes 30 J ° 

 and 47^°, the maximum scale error is only 

 one half of one per cent. Only in southern- 

 most Florida and Texas does this projection 

 attain its maximum scale error of 24 per cent. 

 This implies, however, an error in the areas 

 at these extreme parts equal to the square of 

 the linear distortion, or an error of 5J per 

 cent. 



While this error in area may be accounted 

 for by methods already described, the Zenithal 

 projection on the other hand is free from this 

 inconvenience. 



The choice then between the Lambert 

 zenithal and the Lambert conformal for a 

 base map of the United States, disregarding 

 scale and direction errors which are con- 

 veniently small in both projections, rests 

 largely upon the choice of equal area as rep- 

 resented by the Zenithal and conformality as 

 represented by the Conformal Conic projec- 

 tion — the former projterty appealing directly 

 to the practical use of the map, the latter 

 property being one of mathematical refine- 

 ment and symmetry with definite scale factors 

 available, the projection having two parallels 

 of latitude of true scale, the advantages of 

 straight meridians as an element of prime 

 importance, and the possibilities of indefinite 

 east and west extension without increase of 

 scale error. 



SPECIAL ARTICLES 



SUBSTITUTES FOR PHENOLPHTHALEIN AND 



METHYL ORANGE IN THE TITRATION 



OF FIXED AND HALF-BOUND CO^i 



During the past year the writer has had 

 occasion to make a great many determina- 

 tions of sodium carbonate in the presence of 

 the hydrate by the double titration method 

 with phenolphthalein and methyl orange as 

 indicators. The end point with methyl 

 orange was not satisfactory. A number of 

 new indicators were tried with the result that 

 two were found which may be used as substi- 

 tutes for phenolphthalein and methyl orange. 



1 Published by permission of the Secretary of 

 Agriculture. 



An added advantage of these two indicators^ 

 is that both have the same color changes. Six 

 drops of one indicator in 75 c.c. of solution 

 gives a fairly deep blue in the presence of 

 sodium hydrate and carbonate and on titra- 

 tion with hydrochloric acid retains this color 

 tmtil the hydrate is all neutralized and the 

 carbonate converted into bicarbonate when it 

 changes at the neutral point to a muddy 

 green and then with a slight excess of acid to 

 a lemon yellow. The addition of three drops 

 of the second indicator will noAV change the 

 solution to a deep blue, which continues until 

 the bicarbonate has all been destroyed, when 

 the solution shows the same intermediate 

 change as before and becomes a lemon yellow 

 again when a slight excess of acid is present. 



These indicators are among the nine recom- 

 mended by Clark & Lubs^ for the colorimetric 

 determination of hydrogen ion concentration. 

 The first indicator, thymol blue (thymol sulfon 

 phthalein) is prepared by introducing 1 deci- 

 gram of the substance into a Florence flask 

 and then adding 4.3 c.c. of jj,/20 sodium hy- 

 droxid. The solution is best heated by intro- 

 ducing the flask into hot water and agitating 

 imtil the indicator is all dissolved. When 

 solution is complete, the volume is made up to 

 250 c.c. with distilled water. 



The substitute for methyl orange is brom 

 phenol blue (tetra bromo phenol sulfon 

 phthalein). This indicator is made up in 

 the same way except that 1 decigram requires 

 only 3.0 c.c. of n/20 sodimn hydroxide. 



F. M. SCALKS 



U. S. Depabtment of Aqrictjlt-dee 



THE AMERICAN SOCIETY OF 

 ZOOLOGISTS 



The American Society of Zoologists held its 

 seventeenlth annual meeting in conjunction with 

 Section P of the American Association for the 

 Advancement of Science and the Ecological So- 

 ciety of America, Deeemtjer 29, 30 and 31, in the 

 Soldaji High School building, St. Louis, Missouri. 

 President C. M. Child presided throughout the 



2 These indicators may be obtained from Hyn- 

 son, Westcott & Dunning, of Baltimore, Maryland. 



3 Clark, Wm. Mansfield, and Lubs, Herbert A., 

 Jour, of Bacteriology, Vol. II., Nos. 1, 2 and 3. 



