( 473 ) 
may also be closed at the top by means of a screw. Through this 
tube, salts are introduced into the apparatus. Two of these instru- 
ments are placed in a copper waterbath with two cylindrical openings 
from the bottom to the lid. The edges of the lids of the silvereylin- 
ders rest on the lid of the copper waterbath which is 22 em. in 
height. The bottom of the silver cylinders, therefore, do not fall 
within the plane of the bottom of the copper waterbath. The 
waterbath has a diameter of 24 em. and has besides the two 
cylindrical openings already mentioned, two other holes in the lid ; 
through one of these passes a thermometer and through the other 
the tube of a large condenser. The arrangement is shown in Fig. II. 
Both the condensing tubes A and A’ are connected by means of 
the india-rubber tubes a and a’ with the T piece 7, whilst the latter — 
may be connected with the manostat by means of the tube m. The 
heating of the waterbath takes place by means of two small lumi- 
nous flames of two Bunsen-burners, whilst underneath each silver 
cylinder a Bunsen-burner was placed, the flame of which was so 
regulated that it just touched the bottom of the cylinder. 
As regards the arrangement of the manostat I still have to men- 
tion that I have replaced the aspirator by a water-suction air pump. 
To be able to regulate the diminution in pressure in the suction- 
pipes, I connected it with the following arrangement consisting of a 
glass cylinder closed by a doubly perforated cork. Through the one 
hole passes one of the tubes of a Tpiece which stops just under- 
neath the cork. Through the other hole is introduced a long glass 
tube which may be moved up and down with a little friction. The 
glass cylinder is almost filled with water. If now, the T piece is 
linked to the suctionpipe of the pump, the suction may be easily 
regulated by pushing the long tube more or less down into the 
water. This arrangement works very regularly and easily and for 
my purpose it is preferable to an aspirator. 
The second boiling vessel filled with water serves to keep the 
operator well informed about the action of the manostat. A change 
of pressure in the apparatus of 1 mm. of water causes a change in 
the boiling point of —- 0.003°. 
Preliminary observations with the new Apparatus. 
It was first of all necessary to ascertain what kind of nucleus 
ought to be put into the silver cylinders to present overheating, 
My first trials were made with “shot” but the result was not 
satisfactory as overheating could not be entirely prevented in this 
manner and it seemed to me desirable to choose a substance of a 
