AMERICAN INSTITUTE. 447 



lei to each other in broad arrow-lieacled shafts, serrated on each side, and 

 from these lateral crystals grow, until they interlock with each other and 

 form a magnificent crystalline structure, resembling the promiscuous group- 

 ing of an immense number of fern leaves, placed one upon the other with- 

 out the least regard to regularity, each shining with a soft exquisite pearly 

 whiteness liiie the subdued radiance of the moon. 



GLAUBER SALTS. 



While crystallizing exhibits a singularly great diversity of combinations, 

 it begins in a spicular cluster, and then spreads in needle-shaped crystals, 

 which intersect others, and thus form a perfect lattice work. Sometimes 

 solid crystals radiate from a center, like the spokes of a wagon wheel ; 

 then again they form themselves in rows similar to the teeth of a comb. 



Alum is a substance artificially produced, though it is sometimes found 

 in a native state. The form of its crystals are octahedron — that is to say, 

 they have eight equal sides, replete with elegance and beauty, and as they 

 advance in parallel lines, throw out spires laterally at right angles with the 

 parent crystal ; and from these others start forth and interlace with each 

 other until they form a glittering sheet of graceful gothic arches of incon- 

 ceivable beauty. 



Common salt in solution, as it crystallizes never spreads out into numer- 

 ous beautiful ramifications, but as the liquid evaporates, forms on the sur- 

 face of the glass small sparkling diamonds of eight and twelve-sided fig- 

 ures, by the union of primitive cubical crystals, which sometimes attach to 

 each other, and by degrees build itp a hollow structure in the form of a pyra- 

 mid, and what is very strange, is invariably capped by a single perfect 

 cube. 



Verdigris does not crystallize with the same rapidity that other salts do, 

 because the solution evaporates very slowly, and forms small and large 

 crystals, which cross each other in every direction, in many instances 

 representing a perfect fleur-de-lis, of a fine greenish-blue color. The primi- 

 tive form of the crystals is that of a rhomboid, as well defined and perfect 

 as if cut by the lapidary, and are symmetrical, elegant and beautiful. 



I have examined many minute aquatic creatures with the microscope, 

 and among others the polype, which is found abundantly in brooks attached 

 to aquatic plants. Its body consists of many cells, formed of green mat- 

 ter, possessing to a wonderful degree the power of contraction and expan- 

 sion. Attached to the mouth there are sixteen arms, which the creature 

 employs for the purpose of seizing its food. They appear to the naked eye 

 as thin threads, but through the microscope slender tretles, consisting of 

 numerous cells like the body, usually filled with a fluid. It feeds upon 

 small crustaceous creatures, the structure of which has been so perfectly 

 preserved for ages, that the microscopist readily detects the diiFerent spe- 

 cies, and assigns them without diificulty to their appropriate place in the 

 vegetable kingdom. 



In the Isle of Portland immense forests of pine trees have been trans- 



