m 
ON THE MOLECULE OF WATER. 
In all cases these operations should take place on a warm day, the morning being al¬ 
ways preferable. A slight moisture arising from the morning dew will make the powder 
more easily adhere to the spots where it is applied, and maintain its properties long 
enough to cause the death of the insects. The insufflation should be renewed several 
times .according to the nature and number of insects to be destroyed. The first operation 
generally stupefies them, while at the second or third application they lose their strength, 
fall to the ground, and die sooner or later. 
In order to prevent the ravages of the wheat-midge, the powder is mixed with the 
grain to be sown, in the proportion of about two ounces to two or three bushels, which 
will save a year’s crop. 
For insects in dwellings the insufflation may be performed by bellows of a smaller size 
than those used in agriculture and horticulture. Proper care should be taken to make 
the powder penetrate to the recesses where the insects lodge. Household furniture ought 
to be scrupulously searched, and bedsteads and sofas sprinkled in the evening. By con¬ 
tinuing this for several days, the premises will be thoroughly rid of insects. 
For the preservation of furs, woollen garments, or patterns, it is necessary, at the ap¬ 
proach of spring, to sprinkle the articles abundantly with the powder, the object in con¬ 
templation being, not the destruction of the insects, but the preventing their reappear¬ 
ance. —From the Technologist. 
ON THE MOLECULE OF WATEE. 
BY WILLIAM OGLING, ESQ., M.B., F.R.S. 
( Read at a meeting of the Royal Institution of Great Britain , Friday , May 15, 18G3.) 
Does the molecule of water consist of a single combining proportion of hydrogen 
having the relative weight 1, united with a single combining proportion of oxygen 
having the relative weight 8, or does it consist of two combining proportions of hydrogen 
having each the relative weight 1, united with a single combining proportion of oxygen 
having the relative weight 16? In other words, ought the molecule of water to be re¬ 
presented by the formula HO', in which O' stands for 8 parts by weight of oxygen, or 
by the formula H 2 0", in which 0" stands for 16 parts by weight of oxygen ? The ques¬ 
tion is entirely one of fact. If the hydrogen of water is experimentally indivisible, it 
necessarily constitutes an indivisible proportion, or atomic proportion, or so-called atom. 
If, on the other hand, it is experimentally divisible into two equal parts, it must consist 
of at least two atomic proportions, or two atoms. 
Similar questions with regard to the molecular formulae of other compounds have been 
decided with an almost absolute unanimity. Thus chlorhydric or muriatic acid gas con¬ 
sists of 1 part by weight of hydrogen united with 35*5 parts by weight of chlorine, and 
its molecule is represented by the formula HC1, in which H stands for a single combining 
proportion of hydrogen, and Cl for a single combining proportion of chlorine, having 
35A times the weight of the single combining proportion of hydrogen. 
Phosphoretted hydrogen gas consists of 1 part by weight of hydrogen united with 
10-3 parts by weight of phosphorus. Its molecule, however, is not represented by the 
formula HP', in which H stands for a single combining proportion of hydrogen having 
the relative weight 1, and P' for a single combining proportion of phosphorus having the 
relative weight 10-3 ; but by the formula Mf", in which H 3 stands for three separable 
proportions of hydrogen having each the relative weight 1, and V" for a single indivi¬ 
sible proportion of phosphorus having the relative weight 31. 
Silicated hydrogen gas consists of 1 part by weight of hydrogen united with 7 parts 
by weight of silicon. Its molecule, however, is not represented by the formula HSi', in 
which Si' stands for 7 parts of silicon ; or yet by the formula H^Si'", in which SE'stands 
for 21 parts of silicon, as the resemblance in properties between silicated and phospho¬ 
retted hydrogen might seem to require; but by the formula H 4 Si ,w , in which H, stands 
for four separable proportions of hydrogen having each the relative weight 1, ■while Si' w 
stands for a single indivisible proportion of silicon having the relative weight 28. 
Why then do chemists represent chlorhydric acid, and its prototype fluorhydric acid, 
as each containing one combining proportion of hydrogen; phosphoretted hydrogen, and 
its prototype ammonia, as each containing three combining proportions of hydrogen; and 
