Modifiche

We measured several times (at least 10) the weight both when the pen is loaded and when the pen is unloaded. From the various measurements the weight for a loaded and unloaded pen was obtained by calculating average and standard deviation. There is no point in using the highest value, the perfect filling does not exist, what is an indication of how much in ordinary use the pen actually charges, is the average.

We measured several times (at least 10) the weight both when the pen is loaded and when the pen is unloaded. From the various measurements the weight for a loaded and unloaded pen was obtained by calculating average and standard deviation. There is no point in using the highest value, the perfect filling does not exist, what is an indication of how much in ordinary use the pen actually charges, is the average.

The value when the pen is discharged used to estimate how much liquid remains in the [[feeder]], but we took as an indication of the filling capacity the value with the pen is fully filled, because pens are filled once the ink is finished and no longer reaches the nib, and this also includes the one present in the feeder. However, you can use the value with the pen empty for a fairer comparison with the capacity of the cartridges, as it indicates the capacity of the filling system alone (with cartridges the additional capacity of the ink held by the feeder when it is immersed to charge is not available).  

The value when the pen is discharged used to estimate how much liquid remains in the [[feeder]], but we took as an indication of the filling capacity the value when the pen is fully filled, because pens are filled once the ink is finished and no longer reaches the nib, and this also includes the one present in the feeder. However, you can use the weight of the unfilled pen for a fairer comparison with the capacity of the cartridges, as it indicates the capacity of the filling system alone (with cartridges the additional capacity of the ink held by the feeder when it is immersed in the ink bottle to charge the pen is not available).  

The capacity in ml was then determined using the specific weight of the water which is 0,997 g/ml. The difference between tap water and pure water is below the appreciable limits of the measurement in centigrams, and inessential for the measurement whose accuracy is ±0.02 ml (sum of the systematic error of 0.01 g of the scale in the difference between two measurements, even if the error is always higher for a filled pen weight measurement), for the conversion, however, we can substantially assume an equivalence of 1 g => 1 ml being the difference below the measurement error.  

The capacity in ml was then determined using the specific weight of the water which is 0,997 g/ml. The difference between tap water and pure water is below the appreciable limits of the measurement in centigrams, and inessential for the measurement whose accuracy is ±0.02 ml (sum of the systematic error of 0.01 g of the scale in the difference between two measurements, even if the error is always higher for a filled pen weight measurement), for the conversion, however, we can substantially assume an equivalence of 1 g => 1 ml being the difference below the measurement error.