CHEMISTRY. 



151 



Chemical classes j namely, 1. Ossifications; 2. Intestinal concre- 

 ftxamina- t j ons . 3, B.[j a , . ca l cll li ; 4.. Urinary calculi ; 5. Gouty 



"*"V~'' 1 . Ostl/icatioHS, 



Ossifies- Under this name may be comprehended all the concre- 



tions tjons which make their appearance in the solid parts of 



the animal body. The following are the most remaik- 



abie of these : 



1. Small concretions sometimes form in the pineal 

 gland. They consist of phosphate of lime. 



2. Small concretions sometimes form in the salivary 

 glands. These likewise consist of phosphate of Jime. 



3. Pulmonary concretions are occasionally coughed 

 up by consumptive patients. They consist sometimes 

 of phosphate of lime, sometimes of carbonate of lime, and 

 sometimes of a mixture of both. 



4. Hepatic concretions are composed of phosphate of 

 lime, and a tough animal membrane. 



5. The concretions which sometimes form in the pros- 

 tate-gland are composed of phosphate of lime. 



2. Intestinal Concretions. 



Intestinal Concretions sometimes form in the stomach and intes- 

 eoncre- tines chiefly of the inferior animals. Some of these have 

 tiem. been celebrated under the name of bczoars for their me- 



dical virtue. A great many of them have been analyzed, 

 and no fewer than eight species have been ascertained. 



The first species consist of concretions composed of 

 superphosphate of lime, the second of phosphate of mag- 

 nesia, the third of ammonio-phusphate of magnesia ; the 

 fourth of the yellow matter of bile ; the fifth of a green- 

 coloured resinous matter ; the sixth of small fragments 

 of the boUtus igniurius ; the seventh of balls of hair felt- 

 ed together ; and the eighth of woody fibre. 



S. Biliary Calculi. 



Biliary Hard bodies sometimes form in the gall bladder and 



calculi. gall ducts, and occasion painful diseases. Four kinds of 

 these calculi have been distinguished ; the first kind is 

 composed of a matter resembling spermaceti in appear- 

 ance, soluble in hot alcohol, and crystallizing as the 



Nature. 



alcohol cools. This matter has been called adipocire. riiemical 

 The second kind are angular, because a number of them Examina- 

 exist in the gall bladder together. They are composed 

 of adipocire, with a thin external crust of yellow matter 

 of bile. The thiid kind are of a brown colour, and ars 

 supposed to be composed of the altered yellow matter of 

 bile. The gall stones of oxen usually are of this kind. 

 The fourth kind does not flame, but gradually waste 

 away at a red heat. 



4. Urinary -Calculi. 



It is well known that concretions not unfrequently Urinary 

 form in the urinary bladder, and occasion one of the most calculi, 

 dismal diseases to which the human species is liable. 

 These bodies have been carefully and repeatedly examin- 

 ed by modern chemists, who have found them to be very 

 various in their composition. No less than nine distinct 

 substances have been found. These being mixed in dif- 

 ferent proportions, occasion great variation in the com- 

 position of the calculi. The following are the sub- 

 stances : 



1. Uric acid. 



2. Phosphate of lime. 



3. Phosphate of magnesia-and-ammonia. 



4. Oxalate of lime. 



5. Muriate of ammonia. 



6. Magnesia. 



7. Phosphate of iron. 



8. Silica. 



9. Urea. 



The four first of these constitute by far the most com- 

 mon and abundant ingredients of urinary calculi. 



5. Gouty Concretions. 



It is well known that concretions occasionally make Gouty 

 their appearance in joints long subject to the gout. c . lcre * 

 These concretions, from their colour and softness, are 

 usually distinguished by the name of chalk-stones. They 

 are usually small, though they have been observed of the 

 size of an egg. All of them hitherto examined have 

 been found composed of uric acid and soda, o that they 

 consist of the salt called urate of soda. 



PART III. 



ON CHEMICAL APPARATUS. 



Chemica HAVING in the preceding part of the article given a pret- 

 Apparatus, ty full outline of the prebent state of chemical science, it 

 v^-y-^/ still remains for us to make our readers acquainted with the 

 nature of the apparatus employed by chemists, and with 

 the manner of conducting chemical experiments. We 

 must warn our readers, however, not to be led away by 

 the too common notion, that an expensive chemical ap- 

 paratus is indispensible for making any progress in che- 

 mical investigations. By far the most eminent chemist 

 who has ever appeared, we mean Scheele, conducted his 

 researches, and completed his discoveries, with a very 

 leiider apparatus indeed. The same remark applies to 

 Dr Priestley. And Mr Dalton, one of the most ingeni- 

 ous of the chemical philosophers at present in Britain, 

 has conducted all hi* acute restarclirs, ;.i,d made all his 

 important discoveries, with an apparatus so slender as to 

 astonish every person who has seen it, and is acquainted 

 with the numi ioi.'s and important discoveries made by 

 (bis celebrated philosopher. 



That we may give some interest to this part of our Chemical 

 subject, which is naturally dry and disagreeable; though Apparatus 

 of essential importance, we shall suppose ourselves giving ^~~~Y~^* 

 directions to a young student, who wishes to make a 

 complete set of experiments on every branch of chemical 

 science. Now there are four distinct departments in 

 chemistry, which require each a peculiar apparatus, and 

 which must therefore be described separately. These 

 are heat, gaseous bodies, liquids, and solids. 



CHAP. I. 



Apparatus for Experimenting on Heat. 



1. THE first and most essential instrument for experi- Apparatus 

 menting on heat, is the thermometer, an instrument which, flir e *pri- 

 by the expansion of a liquid confined in a glass tube, in- j^" tlng n 

 dicates the temperature of any substance to which, it is 



