THE CULTIVATOR. 
217 
and volatile, and corrodes animal substances. With 
various bases it forms the salts called acetates. 
Whal is oxalic acid ? 
The oxalic is a peculiar acid found in the juice 
of sorrel, in combination with potash. Several sub¬ 
stances also, and particularly sugar, contain the bases 
of this acid in a convenient form for conversion into 
oxalic acid by combining it with oxygen ; and hence 
it has also been called the acid of sugar. It crystal¬ 
lizes m four-sided prisms, has a very acid taste, and 
is soluble in water. It is composed of oxygen, hy¬ 
drogen, and carbon. 
What are the uses of oxalic acid 1 
Oxalic acid is of service in detaching the presence 
of lime in solution. It is also become an article of 
great consumption with the calico-printers, both in 
the state of crystallized oxalic acid, and in that of 
superoxalate of potash. In combination with earths, 
alkalies, and metallic oxides, it forms the salts called 
oxalates. 
What is tartaric acid 1 
Tartaric acid is a particular acid found in the tar¬ 
tar of commerce.* * It is capable of crystallization, 
and easily soluble in water. It is used by calico- 
printers to discharge false prints. The salts formed 
with it are called tartrates. 
What is citric acid 1 
Citric acid is found in the juice of lemons and seve¬ 
ral other fruits. It crystallizes in beautiful rhomboid- 
al prisms, is extremely acid to the taste, and very 
soluble in water. It is used in various ways for do¬ 
mestic purposes, for medicine,f and in the arts. The 
salts formed with it are called citrates. 
What is malic acid ? 
Malic acid is obtained from the juice of apples, in 
which it exists ready formed.£ It is a very acid, red¬ 
dish-coloured liquid, composed, like the other vege¬ 
table acids, of oxygen, hydrogen, and carbon. It is 
incapable of crystallization, and has not yet been 
brought into any use except as a chemical test. Its 
salts are called malates. 
What is lactic acid ? 
Lactic acid is prepared by a peculiar process from 
milk after the curd has been separated. It is an acid 
of a yellow colour, incapable of crystallization, and 
has not hitherto come into use. The salts formed 
with it are called lactates. The earthy and alkaline 
lactates are all deliquescent salts. 
What is gallic acid 1 
Gallic acid is found in the galls of commerce, and 
in most astringent vegetable substances. It is ob¬ 
tained in thin transparent plates, and in minute nee¬ 
dle-shaped crystals, of an acid austere taste. It has 
the property of precipitating iron, from its solution in 
acids, of a black colour. Its salts are called gal- 
lates. 
What is prussic acid ? 
The prussic is a peculiar acid, composed of hydro¬ 
gen, nitrogen, and carbon. It is a colourless liquid, 
like water, has a sweet taste and does not alter the 
colour of vegetable blues. It is of great use to 
chemists for detecting metals in solution. It is pre¬ 
pared from blood and other animal substances ; and 
when united with iron, forms that beautiful colouring 
substance called prussian blue. 
What is uric acid 1 
The uric or lithic acid is found in human urine.— 
Some of the human calculi are composed entirely of 
this acid. When pure it has neither taste nor smell, 
but it reddens vegetable blues, and combines with 
alkalies and earth. It is a composition of carbon, 
nitrogen, hydrogen, and oxygen. 
How many different distinct acids are there ? 
The number of the acids that are well known 
amounts to about thirty; besides which, a variety of 
substances have been announced, as new acids, by 
some of the foreign chemists, that require to be fur¬ 
ther examined before they be finally admitted into 
this class of bodies. 
What are the uses of these various acids '.? 
The usesS of the acids are so many and important 
- —.. .— — .. . .‘ ----- .9 
* Tartar is procured from vessels in which wine has been 
kept. The tartaric acid appears to be a necessary substance 
in all wine; for it seems from some late experiments that 
must will not ferment if ah the tartaric acid be taken from it. 
All the vegetable acids seem to be formed from the same 
radicals, viz: carbon and hydrogen, and perhaps in some 
there is also nitrogen: the different proportions of these, as 
well as of the oxygen, constitute the whole varieties. 
t Within these few years an important use has been made 
of this acid in medicine. It is said that the largest dose of 
opium may be checked in its narcotic effects, if a proper quan¬ 
tity of citric acid be taken with it; and that with this adjunct 
it induces cheerfulness instead of stupefaction, succeeded by 
gentle and refreshing sleep. Dr. Willich’s Lecture on Diet 
and Regimen, page 339. 
t The malic acid is found not only in apples, but in straw¬ 
berries and other summer fruits. 
§ The acids are such powerful agents in a variety of che¬ 
mical changes which take place in nature and in the arts, that 
it is of the utmost importance to acquire a knowledge of the 
modes in which they operate. Let it be recollected, then, 
that there are two ways in which the acids produce changes ; 
jn the substances with which they are brought into contact, 
jn some cases they effect a union with these substances, and 
that it is impossible to enumerate them. They are 
indispensable to various arts* and manufacturers ;f 
they are employed for culinary purposes,:[ and for me¬ 
dicine :§ they act an important part in the great ela- 
boratory of nature,—they produce that numerous 
class of bodies called salts, and form a great propor¬ 
tion of many of the rocky and mountainous districts 
of the globe we inhabit. 
Do you recollect any instances of acids entering into 
the composition of rocks and mountains ? 
The vast masses of limestone, chalk, and marble, 
which are found in every part of the world, are com¬ 
binations of lime and carbonic acid :|| the mountains 
of gypsum in the vicinity of Paris and elsewhere are 
combinations of lime and the sulphuric acid. IT The 
fluor spar of Derbyshire is composed of lime and the 
fluoric acid ;** * * §§ and there areynasses of common salt, 
both in the eastern and western hemisphere, which 
contain such immense quantities of muriatic acidf f as 
would render every attempt to calculate the amount 
abortive. 
Are you sure that the acids lohich Nature has employ¬ 
ed in the formation of mountains, are of the same kind 
as those which come under our common notice and ob¬ 
servation l 
Yes : any of these native mineral substances may 
be decomposed, and their acids exhibited in a sepa¬ 
rate state for experiment or use.Jj; 
Do you know of any other natural productions which 
contain considerable quantities of any of the acids you 
have described ? 
The large masses of celestine^ and of ponderous 
spar|||| in different parts of the earth contain an incal¬ 
culable quantity of the sulphuric acid ; the cryolite ITIT 
of Greenland is a compound of alumina, soda, and 
the fluoric acid ; and several of the valuable minerals, 
together with some of the precious stones, are com¬ 
binations of the different earths with the chromic or 
the phosphoric acids; not to mention the annua] 
changes which the vegetable kingdom undergoes by 
the formation and subsequent decomposition of the 
vegetable acids. 
You speak of the formation of acids :—Are bodies of 
this class formed and decomposed by the common opera¬ 
tions of nature ? 
become a part of the new compound, without having them¬ 
selves undergone any decomposition. In others they become 
partially decomposed, by affording a part of their oxygen to 
the bodies on which they operate. The formation of salt¬ 
petre or nitre by the addition of nitric acid to potash is an in¬ 
stance of the first of these cases, and the action of the same 
acid on iron will exemplify the latter. 
* Sulphuric acid, in a diluted state, is used by the tanner 
in the operation called scouring; also by the dyer, in a con¬ 
centrated state, for dissolving indigo. It is likewise employ¬ 
ed by hatters. Silk-dyers use it for whitening silks, and for 
giving them a beautiful lustre. The chemist employs it in 
the preparation of nitrous and muriatic acid, and as an agent 
in a variety of processes and decompositions. An account of 
a great variety of other purposes to which sulphuric acid is 
applied in the arts may be seen in my Chemical Essays, vol. 
ii. page 468. 
Nitric acid is used by dyers to make their solutions of tin. 
Silver-refiners employ it in the operation of parting. It is 
also used by gilders, brass-founders, calico-printers,"colour- 
makers, &c. 
Muriatic acid is employed in dying, calico-printing, and 
colour-making. The oxymuriatic acid, in bleaching, and 
sometimes in medicine. 
f The acetic, oxalic, tartaric, citric, gallic, and prussic acids 
are all of them employed in the different manufactures of the 
country. 
£ The acetic, the tartaric, and the citric acids are used for 
culinary purposes. According to some experiments of Dr. 
Macbride, it appears that all the mineral acids in a diluted 
state might be employed with great advantage in preserving 
meat. 
§ Parliament voted a rew ard of £5000 to Dr. Carmichael 
Smyth, for his discovery, that nitrous acid, applied in a state 
of vapour, effectually destroys contagion, especially typhus, 
jail, yellow, and such like fevers. See Dr. Smyth, on The 
Effect of Nitrous Vapour, 8vo. 1799. 
|| Limestone, chalk, and marble, are composed of about 44 
parts carbonic acid, and 56 parts lime. 
If Gypsum is composed of 41| parts of lime, and 58^ of dry 
sulphuric acid. 
** Dr. Thomson analyzed a specimen of fluor spar from 
Northumberland, and found it to consist of lime 67.34, and 
fluoric acid 32.66. 
ft Common salt, when in a state of purity, is composed of 
53J parts soda and 46£ of dry muriatic acid; but the salt of 
commerce is always impure. 
|+ If the pupil be directed to pour a little diluted sulphuric 
acid upon some pieces of marble, the carbonic acid will be 
disengaged, and become evident to the senses. In like man¬ 
ner, lie m .y disengage the fluoric acid from the fluor spar, the 
muriatic acid from rock-salt, and other acids from those mine¬ 
rals in which they are fonud native. A few experiments of 
this kind will serve to show him how abundantly the mine¬ 
ral acids occur in nature. 
§§ Celestine, which occurs in such large quantities in the 
neighborhood of Bristol, is composed of about 57 per cent, of 
strontites, and 43 per cent, of sulphuric acid. 
1111 Ponderous spar, which is found plentifully in Stafford¬ 
shire, Derbyshire, &c. and there called caw/c, is a compound 
of 67 per cent, of barytes, and 33 of sulphuric acid. The 
granular kind consists of 90 per cent, of sulphate of barytes 
and 10 of silica. 
ITIT The cryolite, which is a very rare mineral, found only in 
a dreary and remote region of West Greenland, is, according 
to Vauquelin, composed of 21 per cent, of alumina, 32 of soda, 
and 47 of fluoric acid. 
Many of these bodies are the result of, and formed 
by the action ol vegetable life, such as the malic and 
citric acids ; some are formed principally by chemical 
changes effected on dead vegetable matter, as for in¬ 
stance the acetic ; and others, as the sulphuric, occur 
in the mineral kingdom, and are also formed artificial¬ 
ly, in great abundance. 
Objects, Advantages and Pleasures of Science. 
[From the American Library of Useful Knowledge ] 
* * * Reflect how many parts of the reading, even 
of persons ignorant of all sciences, refer to matters 
wholly unconnected with any interest or advantage to 
be derived from the knowledge acquired. Every one is 
amused with reading a story: a romance may please 
some, and a fairy tale may entertain others; but no be¬ 
nefit beyond the amusement is derived from this source: 
the imagination is gratified; and we willingly spend a 
good deal of lime and a little money in this gratification, 
rather than in rest after fatigue, or in any other bodily 
indulgence. So we read a newspaper, without any view 
to the advantage we are to gain from learning the news, 
hut because it interests and amuses us to know what is 
passing. One object, no doubt, is to become acquainted 
with matters relating to the welfare of tire country; but 
we read the occurrences which do little or not at all re¬ 
gard the public interests, and we take a pleasure in read¬ 
ing them. Accidents, adventures, anecdotes, crimes,and 
a variety of other things amuse us, independent of the 
information respecting public affairs, in which we feel 
interested as citizens of the state, or as members of a 
particular body. It is of little importance to inquire how 
and why these things excite our attention, and where¬ 
fore the reading about them is a pleasure: the fact is 
certain; and it proves clearly that there is a positive en¬ 
joyment in knowing what we did not know before; and 
this pleasure is greatly increased when the information 
is such as excites our surprise, wonder or admiration. 
Most persons who take delight in reading tales of ghosts, 
which they know to be false, and feel all the while to be 
silly in the extreme, are merely gratified, or rather oc¬ 
cupied, with the strong emotions of horror excited by the 
momentary belief, for it can only last an instant. Such 
reading is a degrading waste of precious time, and has 
even a had effect upon the feelings and the judgment.—• 
But true stories of horrid crimes, as murders and pitia¬ 
ble misfortunes, as shipwrecks, are not much more in 
structive. It may he better to read these than to sit 
yawning and idle—much better than to sit drinking or 
gaming, which, when carried to the least excess, are 
crimes in themselves, and the fruitful parents of many 
more. But this is nearly as much as can be said for such 
vain and unprofitable reading. If it be a pleasure to 
gratify curiosity, to know what we were ignorant of, to 
have our feelings of wonder called forth, how pure a 
delight of this very kind does Natural Science hold out 
to its students ? Recollect some of the extraordinary dis¬ 
coveries of Mechanical Philosophy. How wonderful are 
the laws that regulate the motions of fluids! Is there 
any thing in all the idle books of tales and horrors more 
truly astonishing than the fact, that a few pounds of wa¬ 
ter may, by mere pressure, without any machinery, by 
merely being placed in a particular way, produce an ir¬ 
resistible force"? What can be more strange, than that 
an ounce weight should balance hundreds of pounds, by 
the intervention of a few bars of thin iron? Observe the 
extraordinary truths which Optical Science discloses.— 
Can any thing surprise us more, than to find that the 
colour of white is a mixture of all others—that red, and 
blue, and green, and all the rest, merely by being blend¬ 
ed in certain proportions, form what we had fancied ra¬ 
ther to be no colour at all, than all colours together? 
Chemistry is not behind in its wonders. That the dia¬ 
mond should be made of the same material with coal, 
that water should be chiefly composed of an inflammable 
substance; that acids should be almost all formed of dif¬ 
ferent kinds of air, and one of those acids, whose strength 
can dissolve almost any of the metals, should be made of 
the self-same ingredients with the common air we breathe ; 
that salts should be of a metallic nature, and composed, 
in great part, of metals, fluid like quicksilver, butlighter 
than water, and which, without any heating, take fire 
upon being exposed to the air, and, by burning, form 
the substance so abounding in salt-petre and in the ash¬ 
es of burnt wood: these, surely, are things to excite 
the wonder of any reflecting mind—nay, of any one but 
little accustomed to reflect. And yet these are trifling 
when compared to the prodigies which Astronomy opens 
to our view: the enormous masses of the heavenly bo¬ 
dies ; their immense distances; their countless numbers 
and their motions, whose swiftness mocks the uttermost 
efforts of the imagination. 
* * * It is surely a satisfaction, for instance to 
know that the same thing, or motion, or whatever it is, 
which causes the sensation of heat, causes also fluidity, 
and expands bodies in all directions; that electricity, 
the light which is seen on the back of a cat when slight¬ 
ly rubbed on a frosty evening, is the very same matter 
with the lightning of the clouds;—that plants breathe 
like ourselves, but differently by day and by night;—that 
the air which burns in our lamps enables a balloon to 
mount, and causes the globules of the dust of plants to 
rise, float through the air, and continue their race;—in a 
word, is the immediate cause of vegetation. Nothing can 
at first view appear less like, or less likely to be caused 
by the same thing, than the processes of burning and of 
breathing—the rust of metals and burning—an acid and 
rust—the influence of a plant on the air it grows in by 
night, and of an animal on the same air at any time, nay, 
