98 P. Mukerji — Method of detecting free Phosphorus. [No. 2, 



Phosphorus or to contain this iu a free state is introduced through 

 the tube into the bottle, and then the cork is quickly inserted. If an 

 organic mixture suspected to contain free Phosphorus has to be intro- 

 duced, it may be poured in through the thistle funnel, or better still 

 through the neck to which the jet is attached ; the jet is quickly put 

 back into the neck after introduction of the mixture. Soon after the 

 introduction of Phosphorus (free) the gas issuing from the jet is found 

 to glow in a dark room, a sheaf of light emanating from the jet. The 

 liquid inside the bottle glows, and luminous flashes are also seen now 

 and then. If now the cork at the top of the middle tube be removed, 

 the light will sink down through the jet, and the gas escaping at the top 

 of the middle tube will glow. On replacing the cork the glow will re- 

 appear at the jet. By alternately removing and replacing this cork, the 

 glow may be made to move downwards and upwards through the jet at 

 the option of the operator. [If the second form of apparatus is used, it 

 is only necessary to take off and replace the stopcock below the funnel, 

 and the glow will appear alternately in the funnel and at the jet.] 



Fresh quantities of dilute Sulphuric acid and Platinic chloride may 

 be introduced if the glow shew T s sign of ceasing. 



Delicacy of the test : — In one experiment, 7 mgrs. of Phosphorus 

 were cut into two larger and two smaller pieces ; and one of the smaller 

 pieces (about 1*5 mgr.) was introduced into the second form of ap- 

 paratus ; the appearance noted above was observed. After about half an 

 hour the zinc was washed two or three times and kept in the flask under 

 water. About twenty-four hours later this zinc without any further 

 addition of Phosphorus again shewed the glow at the jet and in the 

 funnel. 



In another experiment the first form of apparatus was employed, 

 the capacity of the bottle being a little over a litre. 112 grammes of 

 zinc, 250 c.c. of acid and water, and 30 c.c. of milk were introduced 

 into the bottle ; next 2 mgr. of Phosphorus were introduced. The jet, 

 the middle tube, and the bottle all glowed in the way described above. 

 It may be here stated that Fresenius's limit for Mitscherlich's test is 

 1*5 mgr. of Phosphorus in. 150 grammes of mixture ; the second experi- 

 ment shews that the present method is at least as delicate as Mitscher- 

 lich's. 



Remarks on the process : — The use of nascent Hydrogen as a reagent 

 for the detection of Phosphorus is not new. Valentine mentions it in 

 his Qualitative Analysis ; but his method is not the same as the present 

 method. He observes the green core of the hydrogen jet after ignition, 

 and he does not use a dark room. Moreover, his apparatus is Marsh's 

 Apparatus. His test is not a test of free Phosphorus only but indicates 



