prepared slurry was then placed into the pressurized consistometer and thickening time was measured according to iso 10426 2 standard at a bottom hole circulating temperature of 40 u00b0 c according to api schedule 9 2 recommended practice 10b 1997 the following example demonstrates the accelerating effect of the water soluble cellulose derivatives at 40 u00b0 c a sample b1 was made by the subsequent addition of 167 g of 10 m solution of sodium hydroxide and the blend comprising 569 g of fly ash class c 53 5 g of sodium disilicate into 235 g of water the prepared slurry was then placed into the pressurized consistometer and thickening time was measured according to iso 10426 2 standard at a bottom hole circulating temperature of 40 u00b0 c according to api schedule 9 2 recommended practice 10b 1997 a sample b2 was made by the pre dissolution of 6 3 g of low viscosity carboxymethylcellulose in 235 g of water and subsequent addition into this solution of 167 g of 10 m solution of sodium hydroxide and the blend comprising 569 g of fly ash class c 53 5 g of sodium disilicate the prepared slurry was then placed into the pressurized consistometer and thickening time measurements were performed according at a bottom hole circulating temperature of 40 u00b0 c according to api schedule 9 2 the results are shown in the table 2 below n m designates that the experiment was stopped and measurement was not taken because it took more than 16 h to achieve the consistency of 30 bc bearden consistency.