19 



water furnished l)v the Government ice i^lant showed tlint this 

 water sometimes contained nitrites in considerable quantities. 80 

 water was redistilled from potassium permanganate, collected in a 

 perfectly clean manner, and tested to prove the absence of nitrites 

 and nitrates before use. 



Several samples from a bottle of Kahlbaum's chemically pure 

 sodium chloride were found free from nitrates and nitrites. This 

 was employed throughout the following experiments. 



In testing "peptones" 0.1 gram wa,s dissolved in 10 cubic 



centimeters of pure water, thus 10 cubic centimeters of a 1 i)er cent 



peptone solution were ol)tained. In this way all our stock of 



Witte's "peptone" — eight bottles — and in addition one bottle of 



Griibler's pepton depur. sice, were tested for nitrites. Some of 



the tests were repeated more than once, as indicated in Table I, 



and in the last analysis, when the reactions were sufheiently 



marked, they were compared with the standard sodium nitrite 



colorimetric scale usually employed in the quantitative estimation 



of nitrites. 



Table I. 



•Peptone." 



Witte's peptonuria siccvim 



Witte's peptonum sifcum, pro 

 bacteriologie. 



Peptonum siceum 



Do -. 



j Peptonum siceum, pro bacte- 

 riologie. 

 Peptonum siceum 



Num- 

 ber of 

 bottles, 



Nitrites. 



(In 0.1 gram "peptone.") 



(In 10 cubic centimeters water.) 



Do. 



Do. 



Pepton depur. siceum Griibler. 



/(I) 

 \{2) 

 (1) 

 (2) 

 (3) 

 (1) 

 (2) 

 (1) 

 (2) 

 (1) 

 (2) 

 (3) 

 (1) 

 (2) 



1(3) 



Nitrates. 

 (In 0.1 gram 

 "peptone.") 



Trace W 



0.0000005 gram nitr<>gen j>i>o"e. 



\) 







;) 



Distinct reaction w . ^ . . 



0.0000005 gram nitrogen '/'^"'^ itsieu. 



Do. 



Distinct reaction- 



Trace 



Trace 



Distinct reaction ^None. 



0. 



Tmce:::::::::::::::::::::::!}^"^^'^^^'^'^- 



Trace _ . 



Distinct, but less than 

 0.0000005 gram nitrogen. 



1 



Trace > 



Trace I 



Trace ) 



Trace - / 



-1 



Do. 



Do. 



Do. 



Do. 



These are the only records [ have of a considcrabk> number of 

 such tests, but they suflice to show that nitrites occur in some 

 "peptones" in varying and often considerable (juantities. 



They further show that nitrites may be distributed irregularly 

 throughout the mass of "i)eptone," for when (me sample, for 

 instance, from the surface reacts to the test, another from a deeper 



