180 PERFORMANCE OF THE EXPERIMENT 



The best way is to carry out the boiling in a test- 

 tube for live minutes. It must be boiled energetic- 

 ally, and then filtered through a small hardened 

 filter; after which, at least i c.c. of the i per cent, 

 ninhydrin solution is added to 5 c.c. of the filtrate. 

 Should one have less than 5 c.c. of the filtrate there 

 is no harm in boiling with i c.c. of ninhydrin, 

 because the stricter the conditions of these tests the 

 better. 



Boiling is performed (as described on p. 161) for one 

 minute with the aid of a boiling rod. Only in cases, 

 where the solution gives no traces whatsoever of a 

 violet coloration, can the organ be used, and one must 

 wait half an hour before one can establish its presence 

 or absence. Should the organ not be required for 

 immediate use, it must at once be covered with a 

 layer of toluol. Should this test still give a colora- 

 tion, then the substrate must be boiled over again 

 with five times as much distilled water, until the test 

 shows negative results. 



Now, as many standardized dialysing tubes as are 

 required are placed into empty, dry Erlenmeyer 

 flasks, and about J gnri- of the organ is poured 

 into the tubes. This quantity is previously placed 

 upon a piece of blotting paper, and dried by squeezing 

 it strongly. Were the organ placed in a wet state 

 directlv into the tubes, a reaction which would eive 



o 



a weakly positive result might turn out negative, 



