120 POISONS : THEIR EFFECTS AND DETECTION. [§§ III-II 5 . 
shops for cleansing purposes. It is supplied either in a fairly pure state, 
or as a darkish moist mass containing many impurities. 
§ 111. Bicarbonate of Potash (KHC0 3 ) is in the form of large 
transparent rhombic prisms, and is not deliquescent. The B.P. lead or 
arsenic limit is 5 parts per million. The effervescing solution of potash 
{liquor potassa effervescens) consists of 30 grains of KHC0 3 in a pint of 
water (3 45 grrns. per litre), and as much C0 2 as the water will take up 
under a pressure of seven atmospheres. 
§ 112. Caustic Soda Sodium Hydrate (NaHO).—This substance is 
a white solid, very similar in appearance to potassium hydrate ; it 
absorbs moisture from the air, and afterwards carbon dioxide, becom¬ 
ing solid again, for the carbonate is not deliquescent. In this respect, 
then, tlieie is a great difference between potash and soda, for the former 
is deliquescent both as hydrate and carbonate ; a stick of potash in a 
semi-liquid state, by exposure to the air, continues liquid, although 
saturated with carbon dioxide. Pure sodium hydrate has a specific 
gravity of 2-0 ; it dissolves in water with evolution of heat, and the 
solution gives all the reactions of sodium hydrate, and absorbs carbon 
dioxide as readily as the corresponding solution of potash. 
§ 113. Sodii Carbonas—Carbonate of Soda (Na 2 CO 3 10H 2 O).—The 
pine carbonate of soda for medicinal use is in colourless and transparent 
rhombic octahedrons ; when exposed to air, the crystals effloresce and 
crumble. Lead limit 10 parts per million, arsenic limit 2 parts per million. 
The sodii carbonas exsiccata , or dried carbonate of soda, is simply the 
ordinary carbonate, deprived of its water of crystallisation, which 
amounts to 62-9 o per cent. Lead limit 25, arsenic limit 5 parts per 
million. 
§ 114. Bicaibonate of Soda (NaHC0 3 ) occurs in the form of 
minute crystals, or, more commonly, as a white powder. Lead limit 5, 
arsenic limit 2 parts per million. The carbonate of soda sold for house¬ 
hold purposes is of two kinds—the one, “ seconds,” of a dirty white colour 
and somewhat impure ; the other, “ best,” is a white mass of much 
gieatei purity. Javelle water (Eau de Javelle ) is a solution of hypo- 
cld 01 ite of soda ; its action is poisonous, more from the caustic alkali 
than from the chlorine, and it may, therefore, be here included. 
§ 115. Statistics. Poisoning by the fixed alkalies is not so frequent 
as poisoning by ammonia. Falck has collected, from medical literature, 
27 cases, 2 of which were the criminal administering of Eau de Javelle, 
and 5 were suicidal; 22, or 81-5 per cent., died—in one of the cases after 
twenty-four hours ; in the others, life was prolonged for days, weeks, or 
months—in one case for twenty-seven months. In the five years ending 
1916, in England and Wales there were 11 deaths from poisoning by 
the fixed alkalies, 9 males and 2 females, all due to accident, not a single 
case of suicide or murder. 
