FACTS AND OBSERVATIONS. 
449 
Dangers of Arsenical Green Pigments. — The 
Prefect of Police of the Seine (Paris and environs) has very 
properly issued a notice calling attention to the great danger 
attending the use of these pigments for imparting colours to 
the edges of books and various articles of stationery, to 
which these, specifically, very heavy materials are merely fixed, 
either by thin glue-water or gum. It is a well-known fact, 
the police notice says, that, even when mixed with linseed 
oil, these pigments are liable to become loose and pulverulent 
(unless peculiar precautions be taken) ; and they are alto- 
gether unsuitable for the purposes just named, since they 
dust off, and thus may be inhaled and cause derangements 
of health. The manufacturers of the articles alluded to are, 
if they continue this practice after this day, amenable to 
legal proceedings, correctionally as well as en matiere civile 
(liable for action for damages). — Ibid. 
Use of Hypophosphoric Acid in Agriculture for 
the Purpose of Destroying Noxious Insects. — M. 
Martin proposes, more especially for the purpose of destroy- 
ing the Phylloxera vastatrix , which makes great havoc in the 
vineyards, to apply hypophosphoric acid dissolved in water. 
The makers of phosphorus obtain a quantity of this acid in 
aqueous solution, which is thrown away as waste ; but, since 
the transport of this w^aste liquid is too costly (it may be 
very usefully applied where it can be had with ease), the 
author describes a method of making hypophosphoric acid 
by the slow r combustion of phosphorus. According to his 
experiments, 2 grms. of this acid, dissolved in 10 or 12 
litres of water, is a strong poison for all kinds of insects, and 
not only does not hurt plants, but has the effect of increasing 
the soluble phosphates in the soil. — Ibid. 
The Human Heart. — Professor Haughton, of Dublin, 
has calculated that the total daily work of the human heart 
(the ventricles only) is 124,208 foot tons. It does 50,876 
foot pounds of work per minute for every ounce of its 
weight. — Ibid. 
Sulphuretted Hydrogen. — M. Boillot states that, 
after he had placed sulphur in some jars which he had filled 
with hydrogen, and had passed an electric spark through 
the sulphur, which was thus ignited and volatilized, a per- 
ceptible quantitv of sulphuretted hydrogen was produced. — 
Ibid. 
