142 Scientific Intelligence. 
cent in volume and 50c. c. of each portion was placed in each 
retort in order. The retorts and the pieces of zinc must be care- 
fully cleansed. The experiment may be conduc rey to give either 
the effect of mass of the acid, or of the time of contact; yielding 
in the first place a quantity-curve and in the second a time-curve ; 
the quantity of hydrogen gas collected in the successive Nbr 
giving the required curve, the height of the water column being 
the ordinate in each case. e time-curve is seat a cigs curve, 
usually of a logarithmic form. The quantity-curve has points of 
inflection and consists generally of one or more consecutive hyper- 
bolas, showing (1) that the pe ee of the reaction is not propor- 
tional to the acid-strength; (2) that there is a maximum with 27 
per cent H,SO,, a minimum with 33 per cent and 
mum with per 
bros effect; (3) that the effect of weakening the solution is 
re rapid than an equal Aebe dosas ba of it; (4) that the entire 
rocess is accomplished in three stages repre sented by three 
es; and (5) that, if the aahe-o of zinc has been such as 
pa a ~ fill the cylinder with ihccn "she water remaining 
represents the remaining chemical energy of zinc. e 
e 
simultaneous use of blackboard or lantern curves exactl y drawn 
the significance of the method may be clearly proved. For the 
time-curve, the author prefers the action of acid on zinc and for 
the arp an eurve of the action of agers hydrate upon keris te 
m. Soc., xxxvii, 453, June G. F. 
2. on the Estimation of Zine eid Zinc-dust,—BEItsTEIN te 
AWEIN have suggested a new and simple apparatus for the deter- 
cork through which passes a delivery tube. To this a rubber tube 
is attached ona ee it with a similar tube just passing through 
the cork of a larger bottle of two liters or more capacity. 
S as to deliver the water clear of the bottle. At the bottom of 
the large bottle is an opening by which the water may be drawn 
with the zinc by in lining ie small bottle. Immediatel e 
hydrogen evolved forces the water out of the rs bottle hen 
