272 BULLETIN OF THE BUSSEY INSTITUTION. 
after the mixtures which contained yellow ochre had been placed 
in the cage. 
Gypsum and Plaster of Paris. Mixtures of linseed oil and 
powdered gypsum were eaten rather freely, though somewhat less 
readily than ordinary whiting-putty, apparently because the pow- 
dered gypsum was less fine and smooth. Six or eight balls of the 
mixture of gypsum * and oil were repeatedly eaten in the course 
of one day, and sometimes as many as ten balls were consumed. 
The dung meanwhile was of large size and white color, closely 
resembling that from ordinary putty. Mixtures of plaster of Paris 
and oil were less acceptable. After the three mice had become 
accustomed to the gypsum and oil they were given 9 balls (= 12.4 
orms.) of a mixture of plaster of Paris (72.5 per cent) and oil 
(27.5 percent) and they ate all but 3.5 grms. of it in the course of 
the day. Next day the same quantity of the plaster mixture was 
given them and they ate nearly the whole of it; but when a similar 
quantity was offered on the third day, the animals ate hardly any 
of it, though there was no evidence, other than this refusal, that 
they had suffered any inconvenience from what they had eaten 
previously. 
Sulphate of Baryta was eaten readily in a single trial, and it 
appeared not to do the mice any harm. The sample of sulphate 
employed was a pure precipitated article in the form of a very 
fine and smooth powder. It passed from the animals as large 
white dung, like the whiting and the gypsum and plaster. « 
Silica. Mixtures of pure precipitated dry powdery silica ¢ and 
oil were eaten, though rather sparingly. Three and four balls per 
day were eaten in several instances, but never so many as six 
balls. The dung passed by the animals during the silica trials 
was much less decidedly white than that from the whiting and the 
sulphates. It had a yellowish tint, apparently due to its state of 
aggregation. Unlike the whiting-dung, it did not dissolve with 
effervescence when thrown into muriatic acid. 
Clay. Mixtures of oil and clay of good quality (‘* china clay”) 
were not eaten when first offered to the mice. Marks of the teeth 
of the animals were seen upon the balls, it is true, but no appreci- 
* Prepared by mixing plaster of Paris with water enough to make it ‘‘ set” 
and powdering the mass after it had been dried at 212° F. 
+ Obtained incidentally in the analysis of silicates. 
