Three samples of urine were taken from three mares, and yielded respectively the following proportion of urea: -

1st sample

11.9 parts per 1000

2nd sample

12.4 "

3rd sample

11.38 „

When treated with peroxide of hydrogen and tincture of guaiacum they gave no coloration, showing the absence of blood; when a small quantity of blood was added to the urine the hydrogen peroxide and guaiacum gave a distinct blue coloration.