ACE 



A C I 



ACEROTHE'EIUM. An extinct genus 

 of animals, constituting a link con- 

 necting Palceotherium with Rhino- 

 ceros. 



ACE'SCENT. (adcescens, Lat. acescent, 

 Fr.) That has a tendency to be- 

 come sour spontaneously, or by 

 spontaneous decomposition. 



ACETA'BULUM. (Lat.) 



1. A cavity in a bone formed for 

 receiving the head of another bone, 

 and thus named from its cup-like 

 shape ; it is more particularly used 

 for expressing the cavity in the os 

 innomination, which receives the 

 head of the femur, or thigh-bone. 



2. In botany it is used for the 

 cotyledon. 



ACE'TAET. (from acetum, Lat.) An 

 acid pulpy substance found in some 

 fruits, especially the pear, sur- 

 rounding the core ; it is enclosed 

 in a congeries of small calculous 

 bodies towards the base of the fruit. 



A'CETATE. Any salt formed by the 

 union of acetic acid with a salifi- 

 able base, as acetate of iron, acetate 

 of potash, &c. The acetates are all 

 soluble in water; many of them 

 are deliquescent, and crystallizable 

 with difficulty ; they are decom- 

 posed by the sulphuric acid. 



ACHA'TES. (xa/9, Gr.) The agate. 



ACEOUS. Terminations in aceous and 

 icius, express a resemblance to a 

 material; those in eous indicate 

 the material itself ; as membrana- 

 ceous, resembling membrane ; tufa- 

 ceous, resembling tufa ; membrane- 

 ous, skin itself. 



ACHA'NIA. (from xo^, Gr. ab a, 

 priv. et xa/j/w.) In botany, plants 

 whose corolla does not open. Order 

 Polyandria, class Monodelphia ; 

 natural order Columnifera3. 



ACHELOIS. A genus of fossil shells, 

 described by De Montfort as being 

 of. a conical form, with conical 

 septa, but Parkinson considers its 

 characters not sufficiently ascer- 

 tained at present to warrant its 

 being considered a distinct genus. 



A'CHTEITE. Emerald malachite. 



ACI'CULA. (Lat.) A prickle or fine 

 spine. 



ACI'CTJLAE. In the shape of a needle : 

 rocks of granite, having sharp, 

 needle-like summits, are thus 

 named. 



ACI'CTJLAELY. Needle -like. 



ACID, (acidum, Lat. acide, Fr.) The 

 word acid, originally synonymous 

 with sour, and applied only to bodies 

 distinguished by that taste, has been 

 gradually extended in its significa- 

 tion, and now comprehends all sub- 

 stances possessed of the following 

 properties : 



1. When applied to the tongue, 

 they excite that sensation which is 

 called sourness. 



2. They change the blue colours of 

 vegetables to a red. 



3. They unite with water in almost 

 any proportion, with a condensa- 

 tion of volume, and evolution of 

 heat. 



4. They combine with all the alka- 

 lies, producing effervescence during 

 the combination, and with most of 

 the metallic oxides and earths, and 

 form, with them those compounds 

 which are called salts. 



The acids terminating in ous pro- 

 duce compounds to which the termi- 

 nation ite is given, as, e. g. the 

 combination of sulphurous acid and 

 potassa is a sulphite of potassa ; the 

 acids ending in ie form compounds 

 to which the termination ate is 

 applied ; the combination of sul- 

 phuric acid and potassa is a sulphate 

 of potassa. 



ACIDASPIS. (a/s, cuspis, and ao-??, cly- 

 peus vel scutum, Gr.) The name as- 

 signed by Sir E. Murchison to a genus 

 of trilobites, the generic characters 

 of which he thus describes ; ' ' capitis 

 scutum marginatum, antice sub- 

 truncatum, trituberculatum : tuber- 

 culo media postice in mucronem 

 desinente." Although, says the 

 talented author of the Silurian 

 system, most unwilling to multiply 



