1. The Le Chateliar’s flask which we use for the experiment has the scale readings from 18 to 24 ml and if we use quantity of cement greater than 64 gm the rise in the kerosene level will be more than 24 ml and hence we will not be able to get the rise in kerosene level. So we can not use cement greater than 64 gm.

2. Now coming to the point that we can use cement, less than 64 gm then yes we can use the weight of cement ranging from 50 gm to 64 gm. Using weight less than 50 gm will not give a significant rise in the kerosene level and results can be misleading. Why specifically we are using 64 gm is as it is mentioned in IS 4031 – part 11 to use 64 gm cement for the experiment because using 64 gm will give a good rise in kerosene level i.e. about 21 to 22 and highest reading on the apparatus is 24 only so using 64 gm is safe side. Again the formula for the calculation of specific gravity can be modified as

Specific Gravity = (weight of cement used)/(Rise in kerosene level)

However, also the specific gravity of cement also varies from somewhat 3.15 (for OPC) to 2.90 (for portland-blast-furnace-slag and portland pozzolan cement).

for this, If we consider the rise in kerosene level up to reading 22 then, the weight of cement to be used should be 69.3 gm (for OPC with G = 3.15) to 63.8 gm (for PPC with G = 2.90).

So the weight of cement that should be taken for the experiment should be 64 gm.

Also, there is some calculation in some research paper of cement chemistry where with the help of molecular weight of cement, researchers have calculated the weight to be used for the experiment and it comes out to be 63.9999 gm so taken as 64gm.