106 
POPULAK SCIENCE EEVIEW. 
corpuscles, but from a decrease in the proportion of colomlng matter which 
these globules shall contain. — Vide L’Institut, Oct. 9. 
Tinting Microscopic Structures . — Herr E. Schwartz has addressed a note 
to the Viennese Academy, in which he states that he has discovered a mode 
of obtaining simultaneously two layers of a tissue (such as the stomach) 
with different colouring matter. He did not describe the process, but he 
sent coloured drawings showing the effects produced. He alleged that by 
means of the new process he has been able to discover structures which have 
hitherto been obsciu’ed or lost sight of. 
METALLUEGY, MES^ERALOGY, AND MINHsG. 
Advantages and Disadvantages of Nitro-glycerine . — In a late number of the 
Berg-undnHiittanmannische Zeituiig, Herr Richter 5as contributed a paper of 
some length and of considerable interest, upon the advantages and disadvan- 
tages of nitro-glycerine as a blasting material, a subject of much interest 
since the fatal explosion at Newcastle The conclusion which he has 
arrived at may be thus summed up : — 1. Fewer men are wanted for 
working out a certain sized piece of ground, and fewer holes have to be 
bored than at present. A dearth of miners may to a certain extent be 
remedied in this manner, and less steel and iron -will be used than hitherto. 
2. Nitro-glycerine does not take fire easily, and when lighted bums but 
does not explode, and goes out as soon as the flame with which it had been 
brought in contact is taken away. 3. The holes can be tamped easily, 
quickly, and without danger. 4. The amount of smoke after a blast is small 
compared with that of powder, and workmen can go back at once to the 
place where they have blasted without trouble. This is a considerable 
advantage in places where there is but little draught, and holes can be bored 
and fired singly, which was hitherto almost impossible in consequence of the 
all but impenetrable smoke, and had to be avoided as much as possible. 5. 
Holes that have missed or only partly torn can be retamped and shot off, 
which, with the present arrangements is either impossible or accompanied 
by great danger. Against these advantages must be set the following disad- 
vantages : — a. The gases formed during' the explosion of the nitro-glycerine 
have an injurious effect on the organs of sight and respiration, h. Nitro- 
glycerine explodes on being struck smartly, and easily freezes, c. The 
masses of rock which it removes are mostly very large, and considerable 
time has to be spent in breaking them up. 
Solde?' for Steel . — The best solder for steel for fine work is, says the 
American Artizan, a compound of nineteen parts of silver, one part of copper, 
and one part of brass. Borax is also said to be the most eflScient flux. 
Bock Crystal. — Rock crystal, of very fine quality,* has been discovered in 
Arkansas. Rock crystal is described as the purest vitreous variety of quartz, 
and includes pure regularly-formed crystals of quartz, their most usual form 
being that of hexagonal prisms, surmounted by pyramids. In the United 
States it was first discovered in Herkimer county. New York, and afterwards 
in London county, Virginia, and in the State of Vermont and other localities. 
Vide The Artizan^ Nov. 
