BOUSSINGAULT ON HONEY-DEW. 
3 
saccharine matter collected from the leaves of a Lime. Mannite is 
so easy to detect that I have not the slightest doubt as to its 
presence in the product studied by Langlois. 
Optical observations have shown that the reducing sugar 
detected in Lime-tree manna is not glucose (Grape sugar), of which 
the rotatory power is 56^ in the right-handed direction, but laevulose 
(inverted or fruit sugar), which has a left-handed rotatory power 
of 26.« 
Taking into consideration those substances only which rotate 
the polarised ray, the composition of honey-dew will be : — 
Cane Sugar . . . 
Inverted Sugar 
Dextrine 
July 22. 
August 1. 
48.86 
55.44 
28.59 
24.75 
22.55 
19.81 
100.00 
100.00 
These analyses show that the composition of honey-dew collected 
with several days' interval has not remained the same. IS'o doubt 
one has no right to expect that the composition should remain 
precisely identical ; what, however, is remarkable is the analogy 
■which exists in composition between the honey-dew of the Lime 
and the manna of Mount Sinai analysed by Eerthelot. Its com- 
position is, in fact, identical with that of the honey-dew collected 
on August 1. 
Cane sugar 65 
Inverted sugar ... ... ... ... ... 25 
Dextrine 20 
100 
It is a discovery not without interest to have found the manna 
of Mount Sinai in the Vosges. 
In attempting to compare by analysis the quantity of honey-dew 
existing upon the leaves of the Lime which was affected with the 
saccharine matter contained in the leaves in their normal state, we 
arrived at the following result : — 
In 1 Square Metre of Healthy Leaves : — 
Cane Inverted -np^frinP Weight in 
Sugar. Sugar. i^extrine. Grammes. 
3.57 .86 0.00 4.43 
In Honey-dew Collected from ditto : — 
18.92 7.23 5.62 26.77 
Difference : — 
10.35 6.37 5.62 22.34 
B 2 
