304 REPORT—1890. 
that at the higher temperature by observing the expansion of the liquids 
in bulbs with graduated stems of known capacity; let curves be con- 
structed showing the relation between temperature and volume. 
14. Let spirit, turpentine, petroleum, and vinegar be distilled; the 
temperature during distillation being observed, the gradual rise especially 
in the case of spirits and petroleum will be noted. Fractionally distil 
several times some quantity of spirit and of petroleum; let the relative 
density of each separate fraction be determined, and let the water 
separated from the spirit be characterised by freezing it and determining 
the melting-point of the ice and the boiling-point of the liquid which 
results when the ice melts. 
15. Having directed attention to the fact that heat is ‘used up’ in 
melting ice and boiling water, let determinations be made of the amounts, 
following ‘ Worthington’s Practical Physics,’ for example. 
Studies of Chalk: and other Common Solids. 
1. Call attention to the use made of lime in building and its produc- 
tion from chalk or limestone; slake a lump of lime; exhibit specimens 
and pictures of chalk cliffs or quarries and limekilns—if not to be seen in 
the district. Point out on a geological map those parts of the country 
in which chalk occurs, and those where limestone is met with. Explain 
how chalk is supposed to have been formed and show pictures of the 
forms which are present in it, and, if possible, microscopic slides. Explain 
that whitening, which is purchasable everywhere, is but levigated chalk, 
describe its preparation, and let chalk and sand be separated by leevigation. 
2. Let the conversion of chalk into lime be studied quantitatively. 
For this purpose three to five grams of dried whitening should be weighed 
out in a small platinum dish and heated to full redness in the covered dish 
during an hour over a Fletcher Argand Bunsen burner: the dish is then 
removed from the burner, and after about ten minutes, when cold, is 
weighed ; it is then again heated, say for half an hour, &c.; usually 
there is no further loss. Several experiments should be made in this 
way, so that it may be noted that practically the same percentage of loss 
is incurred and the same amount of lime obtained in each case; and 
similar experiments should be made with chalks from different localities 
(Note A). 
3. At the conclusion of each experiment, the residue should be care- 
fully moistened with distilled water and the effect noticed; usually the 
lime slakes, becoming hot—some limes, however, slake very slowly, and 
the heating is imperceptible. The excess of water should then be driven 
off by heating in a water-oven until the weight no longer diminishes. 
4, In comparing the solvent action of the various liquids previously 
studied, it will probably have been noticed that chalk is dissolved by 
acids—for example, vinegar or muriatic acid—with effervescence; such 
an acid may therefore be used, if necessary, in cleaning out the dish at 
the conclusion of the experiment if any of the solid adhere to it. Then, 
having made it clear that the effervescence is due to the escape of an 
air-like substance or gas, which is conveniently termed chalk-gas, let the 
amount of gas which is given off when the chalk is dissolved in acid be 
determined. For this purpose, the simple apparatus shown in fig. 1 
may conveniently be used. From 1°5 to 2 grams of the chalk is weighed 
out on a small square of tissue paper, which is then folded up at the sides 
