Archive | P RSS feed for this section

PURINE GROUP

A number of socalled cyclic diureides, including uric acid.

Comments are closed

PROTAMINES

The simplest proteins, including salmine and and sturine, as isolated from fish testicles.

Comments are closed

PYRROL

A constituent of bone oil. It is a liquid basic body of the fa ran e group soluble in alcohol and ether; sp. gr. 09669 and boilingpoint 130 degrees C.

Comments are closed

PYRONIUM

A proprietary opacifying substitute for tin oxide in enamels, 3 per cent, of which and 3 per cent, of tin oxide giving better results, it is claimed, than 8 per cent, of tin oxide alone, in leadless enamels and being much cheaper.

Comments are closed

PALMITIC ACID

A constituent of most of the harder fats, inciuding spermaceti, and especially palm oils. It is tasteless, odourless, soluble in hot alcohol and ether, and is obtained in crystals which melt at 634 degrees C. It can be distilied at reduced pressure without hange and when saponified with alkalies forms soaps.

Comments are closed

PICRICACID

30H A poisonous, lemoncoloured, crystalline substance which melts at 122 degrees C. and is largely used in the manufacture of explosives and as a yellow dye for silk and wool. It is prepared by the graduated action of strong nitric acid upon phenol and by the nitration of monochlorobenzol in the presence of sulphuric acid, etc. It explodes with violence when heated or struck, is soluble in alcohol, and sparingly soluble in water, to which it gives a deep yellow colour; meltingpoint, 1220 C.

Comments are closed

PYROMETERS

Instruments for determining high temperatures, such as those of furnaces and the fusingpoints of metals. They are of various classes, including the “contact” or “immersion” type, being so called because one part of the pyrometer is immersed in the heated material; and the “distance” type, in which no such part is immersed. The mercury thermometer is a simple form of the firstnamed class, and can be applied in respect of temperatures up to 500 degrees C. The thermoelectric pyrometer consists of two dissimilar metals in wi re form, at the tip of which is a rod enclosed in a protecting tube, and this receives the heat and is termed the “hot junction,” while the other ends of the two wires are outside the source of heat. The temperature registered on an indicator is the difference between that of the two junctions. Many combinations of metals are available. Nickelchromium alloys are stated to give the highest electromotive force in commercial use, ant: are useful for temperatures up to about 1,360 degrees C.

Comments are closed

PORTLAND STONE

An oolitic limestone calcium carbonate composed of minute grains.

Comments are closed

PENTOSANES

Gums which yield pentoses upon hydrolysis as, for example, cherry gum, which yields /arabinose.

Comments are closed

PILOCARPINE

A crystalline, poisonous alkaloid, soluble in water and alcohol, contained in the leaves and stalks of jaboranui used in medicine an d compounding hair tonics.

Comments are closed