46 
THE PHAEMACEUTICAL JOUENAL. 
[July 16, 1870. 
Carbonic Anhydride 
Ammonia . . . 
Acid carbonate 
Carbonate 
(‘carbonate’). 
(‘subcarbonate’). 
. . 58 
41 
. . 18 
25 + 
34 
100 
100 
These results show that the normal salt he examined 
contained two atoms of water to one of carbonic anhy¬ 
dride. For by accepting the percentage numbers he 
gives for the acid carbonate, and calculating from these 
the numbers for the normal salt with two atoms of water, 
we get just those which he gives. Thus:— 
Carb. A. Am. Carb. A. Am. 
58 : 18 X 2 :: 41 ; 25-4. 
Water. Water. 
58 : 24 x 2 4 i ; 33-9. 
Or putting it in another way: if we apply to his num¬ 
bers for the normal carbonate the correction we know to 
be necessary for those he found for the acid carbonate, 
we get almost exactly the numbers expressing the com¬ 
position of the normal carbonate with two atoms of 
water. The calculated numbers are— 
Acid carbonate. 
Carbonic anhydride . 55-70 
Ammonia . . . . 21* * * § 52 
Water.22-78 
Norm. carb. with 2 O EL. 
38-60 
29-82 
31-58 
100-00 100-00 
He prepared the normal carbonate in two ways, of 
which one was by distilling the commercial carbonate, 
and collecting the first product of the distillation before 
it had been exposed to the air; and the other, by adding 
to a warrn saturated solution of the commercial carbo^ 
nate sufficient ammonia to raise the proportion to the 
proper degree, when, on cooling, the normal carbonate 
was^ copiously precipitated. 
Sir Humphry Davy obtained, in 1799, a salt that 
seemed to be, according to him, the most ammoniacal 
carbonate, and by the first of the methods afterwards 
employed by Dalton, but he did not determine its com¬ 
position. 
half an atom of water, so that it was not a true ammo¬ 
nium carbonate, its formula being— 
(C0 2 ) 2 0H 2 (NH 3 ) 4 . 
lie obtained the same compound also by distilling a 
mixture of sal-ammoniac and sodium carbonate. 
Lastly, in opposition to the general statement to the 
contrary, I myself announced in a paper in the ‘Philo¬ 
sophical Magazine for 1868* that a normal ammonium 
carbonate having the formula 
C0 2 (0H 2 ) 2 (NH 3 L 
could readily be obtained. 
I have already mentioned that Berthollet obtained a 
solution of normal carbonate at an early date. Then, 
the y car before Rose s paper appeared, Scanlanf pointed 
out that the action of water upon more of the commer¬ 
cial salt than it can dissolve furnishes a solution contain¬ 
ing the ammonia in much greater proportion to the car- 
borne anhydride than is in the commercial salt. Dalton, 
however, claimed to have anticipated Scanlan in this 
observation, and the latter admitted the justice of the 
clarm. Rose, in his paper the year after, showed that 
this solution was one of the normal carbonate, with only 
a little acid carbonate, and gave two other methods for 
obtaining a solution of normal salt. One is to boil a 
solution of the commercial carbonate; the other is to 
heat the commercial, carbonate very gently in a retort, 
having its beak dipping under mercury, continuing the 
heat until a great part of the carbonate has volatilized 
and the rest become wholly liquefied, then setting aside 
the liquid in a closed vessel to crystallize (which it con¬ 
tinues to do for some days), and then decanting the 
mother-liquor, which is a solution of normal carbonate 
nee from acid carbonate. That a solution of the normal 
salt can be obtained by distilling sal-ammoniac, pearlash, 
and dilute spirit together, was known to Phillips, and 
perhaps others before him. 
.Lastly, normal ammonium carbonate, in combination 
with magnesium carbonate as a crystalline double salt, 
was prepared by Fourcroy many years ago, and after¬ 
wards by Bucholz.J 
(To be continued.') 
Dr. . Thomson, in the seventh edition of his ‘ System - 
atttQ^I), 3 ^ated that a normal carbona 
G 2 U fi 2 (N H 3 ) 2 , could be formed by mixing togethi 
one volume of carbonic anhydride, two volumes of an 
moma, and one volume of water-vapour. It is vei 
doubtful, however, whether the product thus obtained 
a single substance, as will be seen by the later part 
the present paper. 
In 1834 John Davyf repeated his brother’s exper 
merits, apparently ignorant of what in the meantin 
alton had done, and ascertained the substance obtaim 
by Sir Humphry to be a hydrated compound of tv 
atoms ot ammonia to one of carbonic anhydride E 
also confirmed the above statement of Thomson. 
Hiinefeld, in 1836, j obtained a neutral combination < 
ammonia and carbonic anhydride by distilling the con 
mercial carbonate with aqueous alcohol, but he did n< 
determine its state of hydration. 
Next, in 1839, Heinrich Rose§ also examined the mo 
remote part of the first product of the slow distillation , 
the commercial carbonate, and found it to contain tv 
atoms of ammonia to one of carbonic anhydride- bn 
according to him, there was associated with these on] 
* Yol. ii. p. 384. 
t ‘ Some Experiments and Observations on the Combir 
tions ol Carbonic Acid and Ammonia.’ Edin. New Phil 
Journ. vol. xvi. p. 245. 
| Journ. fur prakt. Chemie, vol. vii. p.25. 
§ Pogg. Ann. vol. xlvi. p. 373. “ Ueber die Verbindmm 
des Ammomaks mit der Kohlcnsaure.” Also Taylor’s £ Scfc 
tific Memoirs,’ vol. ii. p. 98. 
THE PRESENT PROSPECTS OF THE SEWAGE 
QUESTION IN RELATION TO THE PUBLIC 
HEALTH. 
BY HENRY LETHEBY, ESQ., M.B. 
(Read before the Metropolitan Association of Medical Officers, 
of Health , May 21, 1870.) 
(Continued from p. 25.) 
\VTien sewage has a very offensive odour, and is. 
c\ orv ing* marsh, gas and sulphuretted hydrogen, it rarely 
exhibits much sign of animal life, but when it is diluted 
with water and exposed freely to the air, the bad odour 
quickly disappears, and the higher forms of infusoria 
are rapidly developed. This is proof of the salutary in¬ 
fluence of air and water in promoting the less hurtful 
kinds of decay. I have often noticed that where thu 
sedimentary matters of sewage accumulate and putrefy, 
without free access of air, foul gases are evolved, and 
little or no organic life, except of the very lowest kind, 
appears. This was formerly the case with the mud upon 
Qie banks of the Thames, where the only living things 
were monads , vibriones, and fungi; but in the middle of 
the stream, where there was abundance of air and water, 
* Fourth series, vol. xxxvi. p. 125. 
f ‘ Reports of the British Association for 1838.’ Transac¬ 
tions of the Sections, p. 63. 
t Bucholz’s ‘ Gren’s Grundriss der Chemie,’ part i. p. 275 x 
