1900.] P. Maker ji — Method of detecting free Phosphorus. 99 



indifferently either Phosphorus, phosphide, phosphite or hypophosphite, 

 since any one of these substances will give a flame with a green core 

 on treatment with nascent hydrogen, i.e., with zinc and dilute Sulphuric 

 acid. It need hardly be stated that the method described in this paper 

 is not the Blondlot-Dussard Method, since the Hydrogen jet is not 

 ignited, and the appearance observed is not the green core of the 

 flame of burning Hydrogen. The phenomena observed iu the present 

 method are very similar to those described by Orookes in page 489 

 of his Select Methods, Third Edition. Orookes, however, uses a some- 

 what complicated distilling and condensing apparatus, and employs a 

 lamp for distilling the Phosphorus : the lamp again necessitates the 

 use of materials for preventing its light from hindering the observation 

 of the glow. Moreover, in his method, the glow is not tinder control. 

 The apparatus described above is simple ; no lamp is required for 

 heating, and consequently no precaution is necessary, as to the reflected 

 light of the lamp being mistaken for the glow of Phosphorus. Again, 

 the operator can by using the present method make the glow move up 

 and down as often as he likes and with great ease. Finally, there is no 

 risk of explosion, since hydrogen continues to be evolved even when air is 

 sucked in through the jet (by opening the top of the middle tube) • air 

 cannot rush in to any large extent. Lastly, Phosphorus can not only 

 be detected by this method, but it can also be estimated quantitively 

 by passing the vapour thus evolved into silver nitrate solution. 



After determining the exact method in which the present test is to 

 be carried out, the influence of a good many substances upon the glow 

 described above was tried ; and by comparing the results obtained with 

 those stated in connection with Mitscherlich's method by Crookes and 

 others it appears that the present method is superior to Mitscherlich's. 

 This will be seen from what will be stated presently. It may be first 

 of all noted that common bazaar zinc was used ; the zinc contained some 

 Phosphorus in the combined state (and also some Arsenic). Hence in 

 contact with dilute Sulphuric acid the zinc evolved a jet of hydrogen, 

 which burnt with a green core on ignition, but which gave no glow 

 without introduction of free Phosphorus. It follows that for the 

 detection of Phosphorus, it is not necessary to use pure zinc. It may be 

 suggested that steam could be substituted for nascent Hydrogen in the 

 second form of apparatus described above. The objection to steam is 

 that the glow is not as controlable as it is with nascent Hydrogen ; 

 moreover there is the risk of explosion after suction of air through 

 the jet by removing the lamp from below the flask and then re-heating. 

 The risk of explosion will be distinctly greater in presence of mustard 

 oil, phosphoretted hydrogen, &c, and in presence of Iodine, Sulphuretted 



