Sulfanilic Acid. 



3i7 



Barium sulfate and litharge are the best injection media. 

 Baruim sulfate is prepared by precipitating it from barium 

 hydroxide with ammonium sulfate, the precipitation being done 

 at about 57 0 C. This gives a very fine flocculent mass that will 

 enter many of the smaller arteries and veins. An aqueous sus- 

 pension is used. Red lead and litharge are employed in either 

 aqueous suspension or in oil. 



The plates are exposed to the x-rays varying lengths of time 

 depending on the size and density of the object and the amount 

 of current used. 



The paper is illustrated with lantern slides of the prepared 

 objects. 



145 (1892) 



The selective bacteriostatic activity of sulfanilic acid. 



By JOHN W. CHURCHMAN. 



[From the Department of Hygiene, Cornell University Medical School, 



New York City.] 



In a recent communication to this Society report was made 

 of a selective bacteriostatic property exhibited by acid fuchsin. 

 From a study of the effect of this dye on spore-bearing gram- 

 positive aerobes and on the commoner gram-negative bacteria 

 its selective activity was shown to be just the reverse of that ex- 

 hibited by gentian violet and the other basic tri-phenyl-methane 

 dyes: the latter kill the gram-positive aerobes and spare gram- 

 negative bacteria, while acid fuchsin kills the gram- negatives and 

 spares the gram- positive aerobes. 



Magenta is one of the basic tri-phenyl-methanes and has the 

 same effect on bacteria as gentian violet. From magenta, acid 

 fuchsin differs only (so far as chemical structure is concerned) by 

 the presence in its molecule of sulph onic-acid groups. Since the 

 two dyes are — with this exception — identical, and since they 

 have — so far as gram-positive aerobes and the commoner gram- 

 negative bacteria are concerned — exactly opposite effects, it was 

 clearly indicated to determine whether the sulfonic acid groups 

 in acid fuchsin were responsible for its ability to kill gram-nega- 

 tive organisms while sparing gram-positive aerobes. 



