AMYGDALOIDS, a-mig'da-loidz, cellular lavas, the cavities of which have been made by expanding steam before the lavas completely solidified, and which are usually filled with secondary minerals, frequently the zeolites (q.v.). The cavities are called amygdules and the rocks are said to be amygdaloidal. Amyg daloids are characteristically extrusive. On Keweenaw Point, Mich., they are of par ticular interest, because the cavities are filled with native copper and constitute the source of much of the copper mined in that region.
AMYL (from the Latin atitylunt, astarch,a its first-known compounds being obtained by the distillation of fermented starchy matter), an important organic radical having the for mula Call,,, and belonging in the fatty series. It is also called apentyl? because, in the long list of analogous radicals having the general formula amyl is the particular radical in which n = 5. Amyl cannot exist in the free state, but two of its molecules can combine to form the paraffin adecane? CoH22, which is a liquid boiling at about 320° F. The radical amyl can have no less than eight different isomeric forms, and the chemistry of its compounds is correspondingly complicated. Of the many compounds that are known, however, only three are especially important in the arts. These are: (1) Amyl alcohol, (2) amyl acetate and (3) amyl nitrite.
(1) Eight isomeric amyl alcohols are theo retically possible, one for each of the theoret ically possible isomeric forms of the radical itself, and seven of these are actually known. Five of the seven are of no particular import ance in practical chemistry, but the remaining two, known respectively as the "active" and "inactive" amyl alcohols, constitute the greater part of the fusel-oil (q.v.) that is obtained abundantly in the manufacture of potato brandy, and less abundantly in the preparation of many other kinds of distilled liquors. "Active" amyl
alcohol has the formula Clis.CH.C.116.CH,.0H, boils at about 262° F., and takes its name from the fact that it rotates the plane of polarized light to the left. "Inactive" amyl alcohol has the formula (CH,),.CH.CH,.CH,.OH, boils at about F., solidifies at —4° F., and has no effect upon polarized light. These two kinds of amyl alcohol may be obtained, mixed, by washing fusel-oil with water and subsequent rectification. They may then be separated by fractional distillation or by other more exact methods, for which see special treatises.
(2) Amyl acetate (more exactly, "iso-amyl acetate," since six acetates are known) is pre pared by distilling a mixture of the foregoing amyl alcohols with sodium acetate and sul phuric acid. It is a liquid, boiling at about 282° F., and possessing a strong fruit-like smell. It is used for flavoring cheap confectionery.
(3) Amyl nitrite, Calii.NO., may be formed by distilling a mixture of the foregoing amyl alcohols with potassium nitrite and dilute sul phuric acid. It is a yellow liquid, with an ethereal, fruity odor. When its vapor is in haled it paralyzes the vasomotor nervous sys tem and lowers the blood pressure. Amyl nitrite is often administered in the form of glass capsules or "pearls" containing one to three drops, which are crushed in the handker chief and inhaled. It is used in arteriosclerosis, angina pectoris, migraine, asthma, haemorrhage and toxic rise of blood pressure. Its effects are powerful and almost instantaneous, and it. should never be tried except under the guidance of a physician.