Conical measure
Encyclopedia
A conical measure is a type of laboratory glassware
Laboratory glassware
Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories...

 which consists of a conical cup with a notch on the top to allow for the easy pouring of liquids, and graduated markings on the side to allow easy and accurate measurement of volumes of liquid.

They may be made of plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

, glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

, or borosilicate glass
Pyrex
Pyrex is a brand name for glassware, introduced by Corning Incorporated in 1915.Originally, Pyrex was made from borosilicate glass. In the 1940s the composition was changed for some products to tempered soda-lime glass, which is the most common form of glass used in glass bakeware in the US and has...

. The use of the conical measure usually dictates its construction material. Plastic conical measures, commonly referred to as measuring cups are used by patients to measure liquid medicaments for oral administration. Glass and borosilicate conical measures are commonly used when compounding
Compounding
Compounding is the mixing of drugs by a compounding pharmacist to fit the unique needs of a patient...

 by the pharmacy
Pharmacy
Pharmacy is the health profession that links the health sciences with the chemical sciences and it is charged with ensuring the safe and effective use of pharmaceutical drugs...

 profession.

Conical measures are the most commonly used item of glassware used in the preparation of extemporaneous medicaments. They are not as precise as graduated cylinder
Graduated cylinder
A graduated cylinder, measuring cylinder or graduate is a piece of laboratory equipment used to accurately measure the volume of a liquid. Water displacement can be used to find out the volume of a solid. Graduated cylinders are generally more accurate and precise for this purpose than flasks and...

s for measuring liquids, but make up for this in terms of easy pouring and ability to mix solutions within the measure itself.

History

During his experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s, Abū al-Rayhān al-Bīrūnī (973-1048) invented the conical measure, in order to find the ratio between the weight
Weight
In science and engineering, the weight of an object is the force on the object due to gravity. Its magnitude , often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus:...

 of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s, which are very close to modern measurements.
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