392 Transactions. — Chemistry. 



interfere with the success of the experiment. Heat may be at once applied, 

 and before the white fumes have quite disappeared the end of the deHvery 

 tube should be placed under water. The experiment may then be conducted 

 as usual, care being taken when it is finished to withdraw the source of heat, 

 and so allow the water to rush up the delivery-tube into the flask, which 

 latter should not be opened till the water has ceased to flow. The phos- 

 phorus in the deflagrating spoon should be more than is required to combine 

 with the oxygen in the flask, which if of moderate capacity will need a piece 

 about the size of a pea. 



This method of preparing phosphine will be found very useful, even in 

 a well- furnished laboratory ; but its utility will be more especially felt in 

 places where coal-gas is unobtainable. 



Art. LXn. — On a new Form of Burette. By T. A. Mollett. 

 [Read before the Philosophical Institute of Canterbury, 13th October, 1881.] 

 Plate XXXVII., fig. 2. 

 There being now so many forms of burettes from which to make a choice 

 when about to conduct a volumetric analysis, it may appear wholly un- 

 necessary to add another to the list. It will be well, however, to remember 

 that one or two are practically obsolete, their form allowing of but rough 

 and uncertain results. Gay Lussac's burette, which gives far better indica- 

 tions, is of too fragile a nature to be practically useful. Binks's also, 

 though less liable to breakage, is not much handier in use than the previous 

 one, and with it is open to another objection, viz., special means have to be 

 taken to ensure the correct reading of the level of the solution. Mohr's 

 burette, of which several modifications have been introduced, is the one now 

 generally employed ; but when dealing with potassium permanganate it 

 cannot be used. To remedy this defect a glass stopcock has been substi- 

 tuted for the caoutchouc tubing, and this form has now mostly superseded 

 the others previously mentioned, as it also allows of the use of Erdmann's 

 float. The glass stopcock is somewhat liable to fracture, and this form is 

 not so easily cleaned as the original. 



Some years back I devised a burette, an exact description of which I 

 came upon while searching in the " Journal of Science,"* from which I make 

 extract : — 



" A new burette has been lately used in Paris. It CQnsists of an upright 

 tube drawn out to a fine aperture below, like that of Mohr, and supported 

 in the same manner. The opening at the top is fitted with a perforated 



* " Quarterly Journal of Science," vol. iii., n.s. (x.,o.s.), 1873, p. 182. 



