To this is then added so much of either the acid or the neutral sodium hydrosulphite as can be made from 90 lb.
The hydrosulphite of soda referred to above is made in the following way: 4-1/2 lb.
To prepare thehydrosulphite a vessel which is fitted (p.
In some cases hydrosulphite has proved a useful reducing agent; it can be easily prepared from ordinary bisulphite of soda in the following manner.
To this is then added 1 gallon of either hydrosulphite or bisulphite of soda to destroy the free oxygen it contains, and prevent it from oxidising the indigo solution, which is next added.
By mixing with milk of lime, the acidity is neutralised, zinc oxide and calcium sulphite are thrown down, and a solution of neutral sodium hydrosulphite is obtained which is more stable and can be kept longer without decomposition.
The acid solution ofhydrosulphite has the property of rapidly reducing and dissolving indigo, and this solution may be used in dyeing.
Of such vats the copperas and lime and the hydrosulphite vats are examples.
The bisulphite of soda is allowed to act on the zinc as will be detailed when an acid solution of sodium hydrosulphite NaHSO{2}, more strictly hydrogen sodium hydrosulphite, is obtained.
It may be restored to its former conditions by adding somehydrosulphite of soda.
The chemical vats are the easiest to work, and (especially the hydrosulphite vats) are coming to the fore, and are gradually driving out the fermentation vats.
If now indigo is mixed with this solution the sodium hydrosulphite exerts a reducing action on it, forming white indigo and sodium sulphite, a perfectly clear solution being obtained, which may be used in dyeing cotton or wool.
This may most conveniently be done by adding thereto a solution of hydrosulphite of soda, which may be made by mixing 4-1/2 lb.
When zinc dust and bisulphite of soda are mixed together a reaction sets in, the zinc dissolves, and there is formed sodium hydrosulphite and zinc and sodium sulphites.
Should the vat show signs of becoming charged with indigo, indicated by its becoming of a green colour, a little of this hydrosulphite added from time to time will correct it.
Instead of preparing the hydrosulphite, the commercial products may be used with greater convenience, a solution containing 1-4% of the hydrosulphite powder being used, and the skins treated in this until satisfactorily bleached.
This is dehydrated sodium hydrosulphite with the chemical formula, Na2S2O4.
There is a bleaching preparation made in France known as "Redo," which is simply calcium hydrosulphite (CaS2O4).
The Hydrosulphite reduces the Indigotine in the Indigo to Indigo White.
If the hydrosulphite be weighed beforehand and the stock of the same be kept free from damp air, or great heat, for future vats the hydrometer can be dispensed with; it is simply weighed out and added slowly to the water.
If added too quickly the hydrosulphite will cake, fall to the bottom and be difficult to dissolve.
It is a good thing to have hydrosulphite slightly in excess as this prevents premature oxidization; too much will strip off the indigo white already deposited on the yarn.
It has many advantages over thehydrosulphite vat, as it is not nearly so much affected by changes of temperature and weather.
The constituents of the hydrosulphite vat are hydrosulphite of soda, lime and indigo.
It is reduced by hydrosulphite of soda yielding a blue vat, in which cotton and other vegetable fibres are dyed in the same way as in the indigo vat.
The requisite hydrosulphite of soda is prepared by allowing zinc powder (13 lb.
Here again the hydrosulphitetakes up oxygen from the water and liberates the necessary hydrogen.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "hydrosulphite" in a variety of sentences. We hope that you will now be able to make sentences using this word.
